הריני מקבל עלי
את מצות הברא
ואהבת לרעך כמוך
לרעך כמוך!
A Kavvanah Before Prayer
I hereby accept upon myself
the commandment of The Creator
to love my neighbor as myself!
(יז) לֹֽא־תִשְׂנָ֥א אֶת־אָחִ֖יךָ בִּלְבָבֶ֑ךָ הוֹכֵ֤חַ תּוֹכִ֙יחַ֙ אֶת־עֲמִיתֶ֔ךָ וְלֹא־תִשָּׂ֥א עָלָ֖יו חֵֽטְא׃ (יח) לֹֽא־תִקֹּ֤ם וְלֹֽא־תִטֹּר֙ אֶת־בְּנֵ֣י עַמֶּ֔ךָ וְאָֽהַבְתָּ֥ לְרֵעֲךָ֖ כָּמ֑וֹךָ אֲנִ֖י ה':
(17) You shall not hate your brother in your heart; you shall rebuke your fellow, and do not bear a sin because of him. (18) You shall not take revenge, and you shall not bear grudge against the members of your people, you shall love your companion as yourself: I am God.
שוב מעשה בנכרי אחד שבא לפני שמאי א"ל גיירני ע"מ שתלמדני כל התורה כולה כשאני עומד על רגל אחת דחפו באמת הבנין שבידו בא לפני הלל גייריה אמר לו דעלך סני לחברך לא תעביד זו היא כל התורה כולה ואידך פירושה הוא זיל גמור.
Another time a non-Jew came before Shammai and said, "I will convert if you can teach me the entire Torah while I stand on one foot." Shammai pushed the non-Jews aside with the ruler that was in his hand. The non-Jew came before Hillel and Hillel converted him saying, "What is hateful to you, do not do to your neighbor, that is the entire Torah, the rest is just commentary, now go and study."
תנא דבי אליהו רבה כ"ו, ו'
כך אמר להם הקב"ה לישראל. בניי. כלום חיסרתי מכם. מה אני מבקש מכם. הא איני מבקש אלא כדי שתהיו אוהבין זה את זה. ותהיו מכבדין זה את זה. ותהיו יראין זה מזה.
Tana d'Bei Eliyahu Rabbah 26:6
This is what the Holy One said to Israel: My children, what do i seek from you? I seek no more than that you have love for one another, and respect for one another; and that you have reverence for one another
"You shall be perfect with the L-rd your G-d." (Deut. 18:13)
Prayer is considered to be an offering before G-d - an offering of the soul. In the days of the Holy Temple, an animal offered for sacrifice had to be perfect and without defect; in the same way, when a Jew prays, he must also be whole of limb and without blemish. As all Jews are metaphorically part of the same body, if a person rejects his fellow Jew for whatever reason, it is his own self that becomes crippled. Therefore, it is customary to make the verbal declaration before praying: "I hereby accept upon myself the positive commandment of 'You shall love your neighbor as yourself."
Now this inclusion really takes place only when a person demonstrates with his very self and body that he loves his neighbor, like two limbs joined to one another, fulfilling "What's mine is yours," for the other is his own flesh and blood.
This cannot happen when you hate anyone of Israel in your heart; then you separate the portion of that person from your soul, pushing him away in hatred. You remove your will from him, and thus you of necessity have a blemish or a lack in your own soul, a place where that portion is missing . . and you remain blemished . . . then you cannot rise up in an acceptable way before God, as Scripture says: "The one that has a blemish may not draw near to be offered up" (Lev. 21:17). The light of Eyn Sof which contains them all will not bear you, because of the lack in you, since you have left that one out. Eyn Sof, after all, contains him as well....
[This is the meaning of] "Bless us, our Father, all of us as One." For then "You are all beautiful, my beloved, and there is no blemish in you" (Cant. 4:7). Then the union of the Blessed Holy One and His shekhinah is effected, revealing the light of Eyn Sof in the source of Israel's souls, "so that they be One within One..."
This is the secret meaning of "You shall be perfect with the Lord your God" (Deut. 18: 13). Just as God is perfect [simple, whole] with the totality of Israel's souls, shining the light of sublime Hokhmah into these limbs of the shekhinah, loving His neighbor as Himself and disregarding his sins, so must you be whole and simple with your neighbors, so that the Lord may be your God in complete devotion, in Oneness.
This is why Hillel said: "The rest is commentary": all the mitzvot are for the purpose of uniting the Holy One and His shekhinah, as is known.... This union is dependent upon the revealing of true love, so that the other be truly "as yourself," for "His people are a part of God" (Deut. 32:9), as we have explained. And this comes about through the fulfillment of "Love your neighbor as yourself," to which all the other commandments are thus a commentary, spelling out this union.