Rabbi Joseph Albo - The Forgotten Philosopher: What was Moses' sin at the Waters of Meribah?

The incident at Meribah

(א) וַיָּבֹ֣אוּ בְנֵֽי־יִ֠שְׂרָאֵ֠ל כׇּל־הָ֨עֵדָ֤ה מִדְבַּר־צִן֙ בַּחֹ֣דֶשׁ הָֽרִאשׁ֔וֹן וַיֵּ֥שֶׁב הָעָ֖ם בְּקָדֵ֑שׁ וַתָּ֤מׇת שָׁם֙ מִרְיָ֔ם וַתִּקָּבֵ֖ר שָֽׁם׃ (ב) וְלֹא־הָ֥יָה מַ֖יִם לָעֵדָ֑ה וַיִּקָּ֣הֲל֔וּ עַל־מֹשֶׁ֖ה וְעַֽל־אַהֲרֹֽן׃ (ג) וַיָּ֥רֶב הָעָ֖ם עִם־מֹשֶׁ֑ה וַיֹּאמְר֣וּ לֵאמֹ֔ר וְל֥וּ גָוַ֛עְנוּ בִּגְוַ֥ע אַחֵ֖ינוּ לִפְנֵ֥י ה'׃ (ד) וְלָמָ֤ה הֲבֵאתֶם֙ אֶת־קְהַ֣ל ה' אֶל־הַמִּדְבָּ֖ר הַזֶּ֑ה לָמ֣וּת שָׁ֔ם אֲנַ֖חְנוּ וּבְעִירֵֽנוּ׃ (ה) וְלָמָ֤ה הֶֽעֱלִיתֻ֙נוּ֙ מִמִּצְרַ֔יִם לְהָבִ֣יא אֹתָ֔נוּ אֶל־הַמָּק֥וֹם הָרָ֖ע הַזֶּ֑ה לֹ֣א ׀ מְק֣וֹם זֶ֗רַע וּתְאֵנָ֤ה וְגֶ֙פֶן֙ וְרִמּ֔וֹן וּמַ֥יִם אַ֖יִן לִשְׁתּֽוֹת׃ (ו) וַיָּבֹא֩ מֹשֶׁ֨ה וְאַהֲרֹ֜ן מִפְּנֵ֣י הַקָּהָ֗ל אֶל־פֶּ֙תַח֙ אֹ֣הֶל מוֹעֵ֔ד וַֽיִּפְּל֖וּ עַל־פְּנֵיהֶ֑ם וַיֵּרָ֥א כְבוֹד־ה' אֲלֵיהֶֽם׃ {פ}
(ז) וַיְדַבֵּ֥ר ה' אֶל־מֹשֶׁ֥ה לֵּאמֹֽר׃ (ח) קַ֣ח אֶת־הַמַּטֶּ֗ה וְהַקְהֵ֤ל אֶת־הָעֵדָה֙ אַתָּה֙ וְאַהֲרֹ֣ן אָחִ֔יךָ וְדִבַּרְתֶּ֧ם אֶל־הַסֶּ֛לַע לְעֵינֵיהֶ֖ם וְנָתַ֣ן מֵימָ֑יו וְהוֹצֵאתָ֨ לָהֶ֥ם מַ֙יִם֙ מִן־הַסֶּ֔לַע וְהִשְׁקִיתָ֥ אֶת־הָעֵדָ֖ה וְאֶת־בְּעִירָֽם׃ (ט) וַיִּקַּ֥ח מֹשֶׁ֛ה אֶת־הַמַּטֶּ֖ה מִלִּפְנֵ֣י ה' כַּאֲשֶׁ֖ר צִוָּֽהוּ׃ (י) וַיַּקְהִ֜לוּ מֹשֶׁ֧ה וְאַהֲרֹ֛ן אֶת־הַקָּהָ֖ל אֶל־פְּנֵ֣י הַסָּ֑לַע וַיֹּ֣אמֶר לָהֶ֗ם שִׁמְעוּ־נָא֙ הַמֹּרִ֔ים הֲמִן־הַסֶּ֣לַע הַזֶּ֔ה נוֹצִ֥יא לָכֶ֖ם מָֽיִם׃ (יא) וַיָּ֨רֶם מֹשֶׁ֜ה אֶת־יָד֗וֹ וַיַּ֧ךְ אֶת־הַסֶּ֛לַע בְּמַטֵּ֖הוּ פַּעֲמָ֑יִם וַיֵּצְאוּ֙ מַ֣יִם רַבִּ֔ים וַתֵּ֥שְׁתְּ הָעֵדָ֖ה וּבְעִירָֽם׃ {ס} (יב) וַיֹּ֣אמֶר ה' אֶל־מֹשֶׁ֣ה וְאֶֽל־אַהֲרֹן֒ יַ֚עַן לֹא־הֶאֱמַנְתֶּ֣ם בִּ֔י לְהַ֨קְדִּישֵׁ֔נִי לְעֵינֵ֖י בְּנֵ֣י יִשְׂרָאֵ֑ל לָכֵ֗ן לֹ֤א תָבִ֙יאוּ֙ אֶת־הַקָּהָ֣ל הַזֶּ֔ה אֶל־הָאָ֖רֶץ אֲשֶׁר־נָתַ֥תִּי לָהֶֽם׃ (יג) הֵ֚מָּה מֵ֣י מְרִיבָ֔ה אֲשֶׁר־רָב֥וּ בְנֵֽי־יִשְׂרָאֵ֖ל אֶת־ה' וַיִּקָּדֵ֖שׁ בָּֽם׃ {ס}
(1) The Israelites arrived in a body at the wilderness of Zin on the first new moon, and the people stayed at Kadesh. Miriam died there and was buried there. (2) The community was without water, and they joined against Moses and Aaron. (3) The people quarreled with Moses, saying, “If only we had perished when our brothers perished at the instance of ה' ! (4) Why have you brought יהוה’s congregation into this wilderness for us and our beasts to die there? (5) Why did you make us leave Egypt to bring us to this wretched place, a place with no grain or figs or vines or pomegranates? There is not even water to drink!” (6) Moses and Aaron came away from the congregation to the entrance of the Tent of Meeting, and fell on their faces. The Presence of ה' appeared to them, (7) and ה' spoke to Moses, saying, (8) “You and your brother Aaron take the rod and assemble the community, and before their very eyes order the rock to yield its water. Thus you shall produce water for them from the rock and provide drink for the congregation and their beasts.” (9) Moses took the rod from before ה', as he had been commanded. (10) Moses and Aaron assembled the congregation in front of the rock; and he said to them, “Listen, you rebels, shall we get water for you out of this rock?” (11) And Moses raised his hand and struck the rock twice with his rod. Out came copious water, and the community and their beasts drank. (12) But ה' said to Moses and Aaron, “Because you did not trust Me enough to affirm My sanctity in the sight of the Israelite people, therefore you shall not lead this congregation into the land that I have given them.” (13) Those are the Waters of Meribah —meaning that the Israelites quarrelled with ה' —whose sanctity was affirmed through them.
What was the sin according to the Rambam (Maimonides)?
Rambam - Shemoneh Perukim [Eight Chapters] 4:13
You know, also, that G-d said to our teacher Moses, the master of former and later ages, "Because you have not confided in me, to sanctity me", "because you disobeyed My command about the Waters of Meribah", "because you did not sanctify me". All this (G-d said) although the sin of Moses consisted merely in that he departed from the moral mean of patience to the extreme of wrath in so far as he exclaimed, "Hear now you rebels" etc., yet for this G-d found fault with him that such a man as he should show anger in the presence of the entire community of Israel, where wrath is unbecoming. This was a profanation of G-d's name, because men imitated the words and conduct of Moses, hoping thereby to attain temporal and eternal happiness...
Sefer Ha-Ikarrim Chapter 4 (22:2)
According to Maimonides, then, there was a profanation of the Holy Name, for the people would think that G-d was angry with them because they asked for water, although they needed it. Else, they would say, Moses would not have been angry with them for no reason. For anger is an unworthy quality, and it is not likely that the head of the prophets would give way to such a low impulse without reason, far be it! Hence the people would come to think ill of G-d, assuming that He was angry for no good reason. This is the gist of Maimonides’ interpretation, but it is far fetched.
What was the sin according to the Ramban (Nachmanides)?
Nachmanides on Numbers 20:1
The sin of Moses and Aaron in the [matter of the] waters of Meribah is not clearly expressed in Scripture...For since G-d had commanded Moses: "Take the rod," [in Verse 8] it implied that he should smite [the rock] with it, for had He only wanted that he should speak to it, what was [the point of] this rod in his hand?
(ה) וַיֹּ֨אמֶר ה' אֶל־מֹשֶׁ֗ה עֲבֹר֙ לִפְנֵ֣י הָעָ֔ם וְקַ֥ח אִתְּךָ֖ מִזִּקְנֵ֣י יִשְׂרָאֵ֑ל וּמַטְּךָ֗ אֲשֶׁ֨ר הִכִּ֤יתָ בּוֹ֙ אֶת־הַיְאֹ֔ר קַ֥ח בְּיָדְךָ֖ וְהָלָֽכְתָּ׃ (ו) הִנְנִ֣י עֹמֵד֩ לְפָנֶ֨יךָ שָּׁ֥ם ׀ עַֽל־הַצּוּר֮ בְּחֹרֵב֒ וְהִכִּ֣יתָ בַצּ֗וּר וְיָצְא֥וּ מִמֶּ֛נּוּ מַ֖יִם וְשָׁתָ֣ה הָעָ֑ם וַיַּ֤עַשׂ כֵּן֙ מֹשֶׁ֔ה לְעֵינֵ֖י זִקְנֵ֥י יִשְׂרָאֵֽל׃

(5) Then ה' said to Moses, “Pass before the people; take with you some of the elders of Israel, and take along the rod with which you struck the Nile, and set out. (6) I will be standing there before you on the rock at Horeb. Strike the rock and water will issue from it, and the people will drink.” And Moses did so in the sight of the elders of Israel.

Sefer Ha-Ikkarim Chapter 4 (22:3)
This is no proof, for in Horeb [Moses] was told: “And your rod with which you smote the river …,” [Exodus 17:5] and yet it was found necessary to state specifically in the sequel: “And you shall smite the rock.” [Ibid 17:6]. Here too therefore he should have been told to strike the rock if that was the intention, as he was told the first time. The taking of the rod therefore is no proof that he would have to strike, for the rod does not cause the flow of the water by the force of striking, for it is not the natural property of a rod when it strikes a rock to split it and bring out water by the force of the blow. The phenomenon is a miracle, and the waters come out by decree of G-d when the rod is near the rock.
Albo's questions:
  1. What was Moses’ sin at the Waters of Meribah?
  2. How could he have made such a mistake?
  3. What was so serious about Moses’ sin?
  4. Why didn’t G-d forgive Moses and why weren't his prayers accepted?
  5. Why did G-d vow not to allow Moses to enter the Land of Israel?
What was the sin at Meribah according to Albo?

(כד) יֵאָסֵ֤ף אַהֲרֹן֙ אֶל־עַמָּ֔יו כִּ֣י לֹ֤א יָבֹא֙ אֶל־הָאָ֔רֶץ אֲשֶׁ֥ר נָתַ֖תִּי לִבְנֵ֣י יִשְׂרָאֵ֑ל עַ֛ל אֲשֶׁר־מְרִיתֶ֥ם אֶת־פִּ֖י לְמֵ֥י מְרִיבָֽה׃

(24) “Let Aaron be gathered to his kin: he is not to enter the land that I have assigned to the Israelite people, because you disobeyed My command about the Waters of Meribah."

Sefer Ha-Ikkarim Chapter 4 (22:6)
The sin at the waters of Meribah was as stated, that is [Moses and Aaron] did not speak to the rock, as they were instructed. The text proves it, as it says: “Because you disobeyed My command about the Waters of Meribah” [Numbers 20:24]. Such an expression cannot apply to the words: “Hear now, you rebels,” [Ibid 20:10] nor to Moses’ anger, but only to their violation of G-d’s command.
How could Moses and Aaron make such a mistake?
(ו) הִנְנִ֣י עֹמֵד֩ לְפָנֶ֨יךָ שָּׁ֥ם ׀ עַֽל־הַצּוּר֮ בְּחֹרֵב֒ וְהִכִּ֣יתָ בַצּ֗וּר וְיָצְא֥וּ מִמֶּ֛נּוּ מַ֖יִם וְשָׁתָ֣ה הָעָ֑ם וַיַּ֤עַשׂ כֵּן֙ מֹשֶׁ֔ה לְעֵינֵ֖י זִקְנֵ֥י יִשְׂרָאֵֽל׃

(6) "I will be standing there before you on the rock at Horeb. Strike the rock and water will emerge from it, and the people will drink.” And Moses did so in the sight of the elders of Israel.

Sefer Ha-Ikkarim Chapter 4 (22:12)
Moses and Aaron thought that as in Horeb where the waters came out by striking [Exodus 17:6 above], here too they would come out only by striking. [But the two scenarios are not comparative.] On the first occasion the Torah had not yet been given and nature was not yet subject to the Israelites to such an extent. But at the waters of Meribah the Israelites were in the fortieth year in the wilderness making them worthy of having miracles done for them and of having nature submit to them by the mere word of Moses.
Revisiting the sin at Meribah - the prequel

(ו) וַיָּבֹא֩ מֹשֶׁ֨ה וְאַהֲרֹ֜ן מִפְּנֵ֣י הַקָּהָ֗ל אֶל־פֶּ֙תַח֙ אֹ֣הֶל מוֹעֵ֔ד וַֽיִּפְּל֖וּ עַל־פְּנֵיהֶ֑ם וַיֵּרָ֥א כְבוֹד־ה' אֲלֵיהֶֽם׃ {פ}

(6) Moses and Aaron came away from the congregation to the entrance of the Tent of Meeting, and fell on their faces. The Presence of ה' appeared to them,
Sefer Ha-Ikkarim Chapter 4 (22:10)
Moses and Aaron went to the door of the tent of meeting as though they were fleeing from the people, as though they had no idea what to do. This was no doubt a profanation of the divine name and was likely to cause lack of faith in G-d and His Torah on the part of those who witnessed the affair.
What was the consequence of their actions?
(יב) וַיֹּ֣אמֶר ה' אֶל־מֹשֶׁ֣ה וְאֶֽל־אַהֲרֹן֒ יַ֚עַן לֹא־הֶאֱמַנְתֶּ֣ם בִּ֔י לְהַ֨קְדִּישֵׁ֔נִי לְעֵינֵ֖י בְּנֵ֣י יִשְׂרָאֵ֑ל לָכֵ֗ן לֹ֤א תָבִ֙יאוּ֙ אֶת־הַקָּהָ֣ל הַזֶּ֔ה אֶל־הָאָ֖רֶץ אֲשֶׁר־נָתַ֥תִּי לָהֶֽם׃

(12) But ה' said to Moses and Aaron, “Because you did not trust Me enough to affirm My sanctity in the sight of the Israelite people, therefore you shall not lead this congregation into the land that I have given them.”

Sefer HaIkkarim Chapter 4 (22:11-12)
The essence of their sin was they evidenced a lack of faith in G-d’s Providence. One great principle of the Torah and foundation of faith, which is contained in the belief in G-d’s Providence, is that G-d subjects’ nature to the control of believers…Though Moses and Aaron acted as they did by reason of their great humility, not wishing to take any credit unto themselves without the command of G-d, nevertheless it was accounted to them as an iniquity and a lack of faith because of the profanation of the divine name which resulted from it.
Moses' prayer to be allowed into Eretz Yisrael
(כג) וָאֶתְחַנַּ֖ן אֶל־ה' בָּעֵ֥ת הַהִ֖וא לֵאמֹֽר׃ (כד) אדושם ה' אַתָּ֤ה הַֽחִלּ֙וֹתָ֙ לְהַרְא֣וֹת אֶֽת־עַבְדְּךָ֔ אֶ֨ת־גׇּדְלְךָ֔ וְאֶת־יָדְךָ֖ הַחֲזָקָ֑ה אֲשֶׁ֤ר מִי־אֵל֙ בַּשָּׁמַ֣יִם וּבָאָ֔רֶץ אֲשֶׁר־יַעֲשֶׂ֥ה כְמַעֲשֶׂ֖יךָ וְכִגְבוּרֹתֶֽךָ׃ (כה) אֶעְבְּרָה־נָּ֗א וְאֶרְאֶה֙ אֶת־הָאָ֣רֶץ הַטּוֹבָ֔ה אֲשֶׁ֖ר בְּעֵ֣בֶר הַיַּרְדֵּ֑ן הָהָ֥ר הַטּ֛וֹב הַזֶּ֖ה וְהַלְּבָנֹֽן׃

(23) I pleaded with ה' at that time, saying, (24) “O lord ה', You who let Your servant see the first works of Your greatness and Your mighty hand, You whose powerful deeds no god in heaven or on earth can equal! (25) Let me, I pray, cross over and see the good land on the other side of the Jordan, that good hill country, and the Lebanon.”

Sefer Ha-Ikkarim Chapter 4 (20:3-6)
Prayer is one of the commandments of the Torah and rewarded in a general way like any other, nevertheless it is much superior to all the others...It cures illness as in the case of King Hezekiah [II Kings 20:5], saves us from death as when the Israelites sinned with the Golden Calf because of Moses’ prayer [Exodus 32:10], Jonah was saved from the bowels of the fish [Jonah 2:1]. It is efficacious in causing barren women to bear children, such as Isaac’s prayer on behalf of Rebekah [Genesis 25:21] and Hannah [I Samuel 1:20]. It prevails in the time of famine such as for David [II Samuel 21:1], and at a time of war for Hezekiah and Isaiah [II Chronicles 32:20]... [Indeed] there is no other commandment that is good for all things except prayer.
So why wasn't Moses' prayer accepted?
(כו) וַיִּתְעַבֵּ֨ר ה' בִּי֙ לְמַ֣עַנְכֶ֔ם וְלֹ֥א שָׁמַ֖ע אֵלָ֑י וַיֹּ֨אמֶר ה' אֵלַי֙ רַב־לָ֔ךְ אַל־תּ֗וֹסֶף דַּבֵּ֥ר אֵלַ֛י ע֖וֹד בַּדָּבָ֥ר הַזֶּֽה׃ (כז) עֲלֵ֣ה ׀ רֹ֣אשׁ הַפִּסְגָּ֗ה וְשָׂ֥א עֵינֶ֛יךָ יָ֧מָּה וְצָפֹ֛נָה וְתֵימָ֥נָה וּמִזְרָ֖חָה וּרְאֵ֣ה בְעֵינֶ֑יךָ כִּי־לֹ֥א תַעֲבֹ֖ר אֶת־הַיַּרְדֵּ֥ן הַזֶּֽה׃

(26) But ה' was wrathful with me on your account and would not listen to me. ה' said to me, “Enough! Never speak to Me of this matter again! (27) Go up to the summit of Pisgah and gaze about, to the west, the north, the south, and the east. Look at it well, for you shall not go across yonder Jordan."

Sefer Ha-Ikkarim Chapter 4 (21:1)
Moses, was, as we know the greatest prophet, who nonetheless despite praying to G-d that he be allowed to enter the land of Israel, he was not answered…
Sefer HaIkkarim Chapter 4 (22:8)
One who doubts that G-d performs the will of the prophet, the righteous or the pious who is worthy, is virtually casting doubt upon the Torah and one of its principles
Sefer HaIkkraim Chapter 4 (22:6-7)
One great principle of the Torah and foundation of faith, which is contained in the belief in G-d’s Providence, is that G-d subjects’ nature to the control of believers
We find this principle verified in the lives of some pious individuals, such as Rabbi Hanina ben Dosa [who was bitten by a poisoned lizard and yet] the lizard died [Berachot 33a], and who lit vinegar in place of oil on Friday night [Ta’anit 25a]. Rabbi Phinehas ben Yair divided [the Ginai] River [three] times [Chullin 7a], whilst Nachum Ish Gamzo performed multiple miracles [e.g., Ta’anit 21a; Pesachim 22b etc.] etc.
And Moses himself spoke in the aftermath of the incident of Korach and his followers and G-d opened up the ground beneath them [Numbers 16:29-33], even though we are not told that G-d commanded him to do this. All of them demonstrated a reversal of the natural course by displaying complete faith in G-d.
How does this relate to Moses at Meribah?
(ו) וַיָּבֹא֩ מֹשֶׁ֨ה וְאַהֲרֹ֜ן מִפְּנֵ֣י הַקָּהָ֗ל אֶל־פֶּ֙תַח֙ אֹ֣הֶל מוֹעֵ֔ד וַֽיִּפְּל֖וּ עַל־פְּנֵיהֶ֑ם וַיֵּרָ֥א כְבוֹד־ה' אֲלֵיהֶֽם׃ {פ}
(6) Moses and Aaron came away from the congregation to the entrance of the Tent of Meeting, and fell on their faces. The Presence of ה' appeared to them,
Sefer Ha-Ikkarim Chapter 4 (22:8)
A prophet who is worthy to perform miracles [but] refuses to do so when he can save a nation or a community, is surely responsible for casting a doubt upon the belief. For the bystander will think that there is no truth in the biblical statements, made in many places, that nature is subject to those who perform the commandments of the Torah, and this will lead to doubting the Torah.
The contrast with Moses' successor, Joshua
(יב) אָ֣ז יְדַבֵּ֤ר יְהוֹשֻׁעַ֙ לַֽה' בְּי֗וֹם תֵּ֤ת ה' אֶת־הָ֣אֱמֹרִ֔י לִפְנֵ֖י בְּנֵ֣י יִשְׂרָאֵ֑ל וַיֹּ֣אמֶר ׀ לְעֵינֵ֣י יִשְׂרָאֵ֗ל שֶׁ֚מֶשׁ בְּגִבְע֣וֹן דּ֔וֹם וְיָרֵ֖חַ בְּעֵ֥מֶק אַיָּלֽוֹן׃

(12) On that occasion, when the LORD routed the Amorites before the Israelites, Joshua addressed the LORD; he said in the presence of the Israelites: “Stand still, O sun, at Gibeon, O moon, in the Valley of Aijalon!”

Sefer Ha-Ikkarim Chapter 4 (22:11)
When Joshua was in a similar predicament, he did not wait for divine permission or advice, but relied on God that He would do his will...G-d confirmed his word, and the Tanakh even says that such a great event did not happen even in the days of Moses and Aaron [Joshua 10:13-14] ...which alludes to their lack of faith because they refused to act of their own accord without divine authority.
Moses and Aaron's second sin
(ח) קַ֣ח אֶת־הַמַּטֶּ֗ה וְהַקְהֵ֤ל אֶת־הָעֵדָה֙ אַתָּה֙ וְאַהֲרֹ֣ן אָחִ֔יךָ וְדִבַּרְתֶּ֧ם אֶל־הַסֶּ֛לַע לְעֵינֵיהֶ֖ם וְנָתַ֣ן מֵימָ֑יו וְהוֹצֵאתָ֨ לָהֶ֥ם מַ֙יִם֙ מִן־הַסֶּ֔לַע וְהִשְׁקִיתָ֥ אֶת־הָעֵדָ֖ה וְאֶת־בְּעִירָֽם׃

(8) “You and your brother Aaron take the rod and assemble the community, and before their very eyes order the rock to yield its water. Thus you shall produce water for them from the rock and provide drink for the congregation and their beasts.”

(יא) וַיָּ֨רֶם מֹשֶׁ֜ה אֶת־יָד֗וֹ וַיַּ֧ךְ אֶת־הַסֶּ֛לַע בְּמַטֵּ֖הוּ פַּעֲמָ֑יִם וַיֵּצְאוּ֙ מַ֣יִם רַבִּ֔ים וַתֵּ֥שְׁתְּ הָעֵדָ֖ה וּבְעִירָֽם׃ {ס}

(11) And Moses raised his hand and struck the rock twice with his rod. Out came copious water, and the community and their beasts drank.

Sefer Ha-Ikkarim Chapter 4 (22:11)
[Moses and Aaron] compounded their sin [i.e., that they evidenced a lack of faith in G-d’s Providence] with a further sin, when they struck the rock, and thereby twice transgressed the command of G-d. For if they had spoken, the name of G-d would have been sanctified and they would have made good part of their error. But not having spoken, they added to their sin.
Why wasn't Moses' forgiven?
(מט) עֲלֵ֡ה אֶל־הַר֩ הָעֲבָרִ֨ים הַזֶּ֜ה הַר־נְב֗וֹ אֲשֶׁר֙ בְּאֶ֣רֶץ מוֹאָ֔ב אֲשֶׁ֖ר עַל־פְּנֵ֣י יְרֵח֑וֹ וּרְאֵה֙ אֶת־אֶ֣רֶץ כְּנַ֔עַן אֲשֶׁ֨ר אֲנִ֥י נֹתֵ֛ן לִבְנֵ֥י יִשְׂרָאֵ֖ל לַאֲחֻזָּֽה׃ (נ) וּמֻ֗ת בָּהָר֙ אֲשֶׁ֤ר אַתָּה֙ עֹלֶ֣ה שָׁ֔מָּה וְהֵאָסֵ֖ף אֶל־עַמֶּ֑יךָ כַּֽאֲשֶׁר־מֵ֞ת אַהֲרֹ֤ן אָחִ֙יךָ֙ בְּהֹ֣ר הָהָ֔ר וַיֵּאָ֖סֶף אֶל־עַמָּֽיו׃ (נא) עַל֩ אֲשֶׁ֨ר מְעַלְתֶּ֜ם בִּ֗י בְּתוֹךְ֙ בְּנֵ֣י יִשְׂרָאֵ֔ל בְּמֵֽי־מְרִיבַ֥ת קָדֵ֖שׁ מִדְבַּר־צִ֑ן עַ֣ל אֲשֶׁ֤ר לֹֽא־קִדַּשְׁתֶּם֙ אוֹתִ֔י בְּת֖וֹךְ בְּנֵ֥י יִשְׂרָאֵֽל׃

(49) Ascend these heights of Abarim to Mount Nebo, which is in the land of Moab facing Jericho, and view the land of Canaan, which I am giving the Israelites as their holding. (50) You shall die on the mountain that you are about to ascend, and shall be gathered to your kin, as your brother Aaron died on Mount Hor and was gathered to his kin; (51) for you both broke faith with Me among the Israelite people, at the waters of Meribath-kadesh in the wilderness of Zin, by failing to uphold My sanctity among the Israelite people.

Sefer Ha-Ikkarim Chapter 4 (22:13)
Since the initial sin involved lack of faith and profanation of the Holy Name, it was not subject to forgiveness as our rabbis’ state: “But if one is guilty of profanation of the Holy Name, repentance has no power to suspend punishment, nor can suffering wipe out the guilt, death alone erases the stain.” [Yoma 86a]. Therefore, G-d made a decree with an oath, and for this reason neither Moses’ prayer nor his repentance availed him in this sin.
Returning to our questions:
  1. What was Moses’ sin at the Waters of Meribah? Moses and Aaron didn't speak to the rock and rebelled against God's command.
  2. How could he have made such a mistake? They thought that as in Horeb where the waters flowed when they struck the rock, so too the water would flow only when they struck the rock.
  3. What was so serious about Moses’ sin? They lacked faith in G-d's Providence and shouldn't have asked G-d what to do in the first place, but acted like Joshua later did at the battle of Gibeon.
  4. Why didn’t G-d forgive Moses and why weren't his prayers accepted? There were in effect two sins. The striking of the rock was actually the second sin. But the first was Moses' failure to act rather than ask, which was a profanation of G-d's Name.
  5. Why did G-d vow not to allow Moses to enter the Land of Israel? A profanation of G-d's Name by a prophet, let alone the prophet par excellence, causes a doubt upon belief amongst the masses and as such neither prayer nor repentance can be effective.