Midrash su Salmi 89:2

(Exodus 15:13) "You have led forth in lovingkindness (chesed)": You have done chesed with us, for we were without (redeeming) deeds, viz. (Isaiah 63:7) "The lovingkindnesses of the L rd will I proclaim, etc.", (Psalms 89:2) "The lovingkindnesses of the L rd will I ever sing, etc." And the world in its very beginning was built only with chesed, viz. (Ibid. 3) "I said that the world (with) chesed will be built." (Exodus, Ibid.) "this people whom You have redeemed": For all the world is Yours, and You have no people but Israel, viz. (Isaiah 43:21) "This people have I created for Myself, etc." And thus is it written (Song of Songs 6:8) "Sixty are the queens and eighty, are the concubines": "Sixty are the queens" — These are the sixty ten thousands (of Israel, who left Egypt); "and eighty, the concubines" — those below the age of twenty; "and young maidens without number" — the minors, who are numberless. Notwithstanding this, (only) "one is My dove" — Moses, who countervails them all. Once, Rebbi was sitting and expounding that one woman bore sixty ten thousands, when a disciple interjected: Rebbi, who is greater, the world or the tzaddik? Rebbi replied: The tzaddik. How so? When Yocheved bore Moses, he countervailed the entire world. And where do we find that Moses countervailed the entire world? In (Numbers 26:4) "as the L rd commended Moses and the children of Israel", and "Then sang Moses and the children of Israel", and (Devarim 34:10) "And there arose no prophet again in Israel like Moses." (Exodus, Ibid.) "You have guided (them) in Your strength": in the merit of the Torah which they are destined to receive, "strength" being Torah, viz. (Psalms 29:4) "The L rd will give strength to His people; the L rd will bless His people with peace" and (Ibid. 99:4) "… and the strength of the King (i.e., Torah) who loves justice."

Rabbi Miasha said: Cain was born, and his wife, his twin-sister, with him. Rabbi Simeon said to him: Has it not already been said, "And if a man shall take his sister, his father's daughter, or his mother's daughter, and see her nakedness, and she see his nakedness; it is a shameful thing"? (Lev. 20:17). From these words know that there were no other women whom they could marry, and these were permitted to them, as it is said, "For I have said, The world shall be built up by love" (Ps. 89:2). With love was the world built up before the Torah had been given. Rabbi Joseph said: Cain and Abel were twins, as it is said, "And she conceived, and bare (with) Cain" (Gen. 4:1). At that hour she had an additional capacity for child-bearing (as it is said), "And she continued to bear his brother Abel" (Gen. 4:2).