Why do we read Megillat Ruth on Shavuot?

(8) But Naomi said to her two daughters-in-law, “Turn back, each of you to her mother’s house. May the LORD deal kindly with you, as you have dealt with the dead and with me!

(16) But Ruth replied, “Do not urge me to leave you, to turn back and not follow you. For wherever you go, I will go; wherever you lodge, I will lodge; your people shall be my people, and your God my God.

(1) 312 On the second day, we complete the Hallel. [We say] the full Kaddish. And we sit and read the Scroll of Ruth. [We do so] because it is written in it (Ruth 1:22), "at the beginning of the barley harvest" - corresponding to [Shavuot], which is called, "the first fruits of the wheat harvest" (Exodus 34:12). And some say it is because Ruth converted, as it is written (Ruth 2:12), "under whose wings you have sought refuge”; and we say in [the chapter entitled] HaCholetz that Naomi said to her, "It is forbidden for us to go outside of the Shabbat perimeter." She said to her, "Where you will go, I will go" (Ruth 1:16), etc. And the Israelites converted on [Shavuot] and entered under the wings of the Divine Presence with the receiving of the Torah. Additional comment: And in Midrash Ruth, we say, "Why is Ruth said on [Shavuot], at the time of the giving of the Torah? To teach you that the Torah was only given through afflictions and poverty." And so did Rav Yehudah ben Barzilai write in his [book of] laws: That when Israel left Egypt, they were redeemed through afflictions; and so too Ruth - "there was a famine in the land" (Ruth 1:1) - and she received the Torah when she converted. And in Tractate Soferim (14:3), we say, "One who reads from Ruth, the Song of Songs, Ecclesiastes, Lamentations and from the Scroll of Esther, must recite [the blessing that concludes], 'concerning the reading of the Megillah' - even though it is included in the Writings. But one who reads from the Writings must recite, 'Blessed are You, Lord our God, King of the universe, who has sanctified us with Your commandments and has commanded us to read in the Holy Writings.'" Additional comment: [After] they read the Scroll of Ruth, the youth (in mourning) says Kaddish, without [the section that begins,] titkabal, and we [then] take out two Torahs. We read [the portion that begins], "Every firstborn" (Deuteronomy 15:19). But if it is Shabbat, we begin with [the portion that begins], "You shall surely tithe" (Deuteronomy 14:22) - to enlarge [the reading] for the tally of seven (who go up to read from the Torah when it is Shabbat). And the maftir (the concluding Torah reading) is, "And on the Day of the First Fruits" (Numbers 28:26), like that of yesterday. And he concludes in Habakkuk up until, "For the leader; with instrumental music" (Habakkuk, 3:19). ([It is] the end of Habakkuk) - it is because it is written there, "God is coming from Teiman" (Habakkuk, 3:3). And we give out charity only for the living. Additional comment: It is because they read today, "Everyone according to the gift of his hand, etc." (Deuteronomy 16:15). And likewise is it the custom every last day of the festivals - since we read this section - to give out charity only for the living, but not for the [sake of the] dead, so as not to grieve over them. For it is written about the festivals (Deuteronomy 16:15), "and you shall be just happy." And likewise is it the custom in Ashkenaz that we do not give our charity for the dead on the three festivals, but rather only on Yom Kippur. [And then] Ashrei. [Then] Kaddish. Until deamiran. And we pray the additional service (Musaf). Like that of yesterday.

(7) Regarding the Reading of the Book of Ruth on Shavuot:

(8) This is really about the Oral Torah. The Kadosh Barukh Hu wants the children of Israel to expand the Written Torah through their deeds--for we know that the deeds of the righteous are “Torah”. Through the deeds of Boaz and Ruth, a scroll was produced by Divine Guidance.

(9) It is written “And Elohim said...saying”, meaning: the children of Israel said words like these to themselves. It’s also written “who gave us a Torah of truth, and within us, planted eternal life”--this refers to Oral Torah, the unique quality of Torah which is Israel’s. They have a unique intellectual approach to understand secrets within the Torah which are hidden and not explicit within the Torah itself.

(10) This itself is the matter of Boaz, whose name means Bo Oz--strength within him--that is to say, he had deep faith in the words of the Sages who explained “an Amonite--excluding an Amonitess”. He had no doubt in the matter, like Ploni did who said “lest I endanger my inheritance”. On the contrary! He was ecstatic to show that the interpretation of the Rabbis was the Torah given on Sinai.

(11) “Trust in the Sages” is the foundation of Oral Torah, and this is what is meant by “Truth and Trust”. Written Torah is explicitly exoteric. Yet, it is the will of the Divine that in this downcast world, Israel achieve ‘truth’ by way of ‘trust’.

(12) The ego gives itself over to remove that trust from a person. It makes it seem in one’s eyes as though they are alienated from Hashem Yisbarakh, and tells them that it is arrogant to even try to seek Hashem Yisbarakh in silent prayer, and the like. But the truth is the exact opposite! Seeking God at all fosters the fear of Heaven.

(1) Blessed be he that took note of you. [I.e.,] the owner of the field who showed you favor [and allowed you] to glean in his field.

(1) And his heart was jubilant. Because he engaged in Torah [study].

(15) And he said, “Hold out the shawl you are wearing.” She held it while he measured out six measures of barley, and he put it on her back. When she got back to the town,