Hear, O Israel: The Lord our God, the Lord is one. Rashi explains that He is our God and not the God of the nations; in the future, the Lord will be one. Explanation of the matter, as Rabbi Acha bar Chanina says, it is written, On that day, the Lord shall be One (Zechariah 14:9). Is He not One now? Rather, [it means that] the World to Come will not be like this world. For in this world, over good tidings one says, “Blessed is He who is good and does good,” and over bad tidings one says, “Blessed is the true Judge.” But in the World to Come, for all events they will say, “He who is good and does good” (Pesachim 50a). Because in this world, since people see opposite actions — to harm or to benefit — therefore some of them have gone into heresy, saying there are two authorities, for from a single source two opposites cannot emerge, as explained above in Genesis (1:5) on the verse And there was evening and there was morning, one day. But in the World to Come, when all troubles will have been forgotten, and everyone will praise and say for good tidings, “He who is good and does good,” and they will not see opposites, therefore the Lord will be One in everyone’s mouth and His name One. For the change in names from judgment to mercy causes them this error. Therefore, The Lord our God — that is, the name of judgment and the name of mercy that only Israel attributes to one God — and in the future the Lord shall be One, for all will use only the name of mercy.

Hashem is One. In the word “Shema” the letter “Ayin” is large, and in the word “Echad” the letter “Dalet” is large, hinting at what they said in the Midrash (Tosafot Chagigah 3b, s.v. “Mi K’amcha”) that the Holy One, blessed be He, and Israel bear witness to each other, etc., as it is written (Isaiah 43:10), You are My witnesses, says Hashem. And our Sages of blessed memory said that the Holy One, blessed be He, showed Moses the knot of [His] tefillin (Berachot 7a). The meaning of this knot is as explained (ibid.) regarding what is written in the tefillin of the Master of the Universe, etc. And it concludes there that it is written in them, You have distinguished Hashem today and Hashem has distinguished you today (Deuteronomy 26:17-18). The Holy One, blessed be He, said, “You have made Me a singular entity in the world through Hear O Israel, Hashem our God, Hashem is One, and I will make you a singular entity in the world, etc.” This is the concept of the knot of tefillin, because just as we bind as a seal upon our heart and arm the unity of the Holy One, blessed be He, so too does the Holy One, blessed be He, place us as a seal upon His heart and as a seal upon His arm, to make us one nation in the land. This is the bond between us and our Creator, may He be blessed, that we both testify to each other regarding the matter of unity, in the manner that “as one comes to see, so does one come to be seen.” This is a correct idea according to the simple meaning.

However, by way of allusion, one can say, regarding the secret of the large Ayin and Dalet and the matter of the knot of tefillin: Moses requested and said, Show me now Your glory (Exodus 33:18), and they said (in Vayikra Rabbah 45:5) that he asked to see the entire reward of the righteous in this world and in the World to Come, for there the honor of the wise will be inherited. God responded to him, You will see My back, but My face shall not be seen (Exodus 33:23). Our Sages said (Berakhot 7a) that My back refers to the knot of the tefillin. For in the tefillin there is the name of Shadai, namely, the Dalet in the knot of the tefillin at the back, and the Yod and Shin are letters that appear in the front — the Shin in the head tefillin and the Yod in the hand tefillin. The letters Yod-Shin spell “yesh” [existence/substance], which alludes to the reward of the World to Come, as it is said (Proverbs 8:21), to bequeath to those who love Me substance [yesh]. For in it there is true existence and substance, and compared to it, the reward of this world is considered void and nothingness. This is alluded to in the Dalet, for its advantage comes from all four (dalet = 4) directions of the world, as it is written (Genesis 28:14), You shall spread out westward and eastward, etc. And God said to him, You will see My back — the Dalet in the knot of tefillin, alluding to the reward of this world. That alone you will be able to see, and it is a secondary matter designated as back. Similarly, He said to Moses, Go up to the top of Pisgah and lift your eyes westward, northward, southward, etc. — to show him all of His back, as Rashi explained in the portion of V’zot HaBerachah (34:1-2), And He showed him all the land, etc., until the Western Sea. And not including [the Western Sea [yam acharon]], because from the last day [yom acharon] and onward is the beginning of the reward of the World to Come, about which it is said (Isaiah 64:3), No eye has seen, O God, besides You. Therefore it is said, but My face shall not be seen. For on the face of the tefillin is engraved the word “yesh,” which alludes to the reward of the World to Come that no eye has seen. This is the secret of the large Ayin and Dalet — to say that the Ayin [eye] of a person cannot see anything except the Dalet, as mentioned. But “yesh” is alluded to in the first letters of the words of “Shema Yisrael,” for the “yesh” that alludes to the inheritance for those who love Him cannot be seen by the eye, but only heard by the ear. We have heard this promise from scribes and storytellers, but the eye has not seen it. This is a precious allusion.

Another explanation for why the letters ayin and dalet are large [in the Shema]: According to what is said in Job (24:8-9), Behold, I go forward, but He is not there; and backward, but I cannot perceive Him; on the left hand, when He works, I cannot behold Him; He hides Himself on the right hand, that I cannot see Him. All this is proof of God’s oneness, that He is not visible in any particular place as opposed to another place, therefore He is not corporeal. And since the eye that sees in all four directions cannot see Him from there because He is not a divisible body, this is proof of His oneness, blessed be He.