מדרש על בראשית 18:16

And it came to pass, when Pharaoh had let the people go (Exod. 13:17). The word let go (shallah) indicates “to escort,” as in the verse Abraham went with them to bring them (leshalleham) on the way (Gen. 18:16). Similarly it states; And Isaac sent them away (vaye-shallehem), and they departed from him in peace (ibid. 26:31). Why does this scriptural portion open with this verse? Because the mouth (i.e., Pharaoh) that had declared: And moreover, I will not let Israel go (Exod. 5:2), now retracted and said: I will let you go (ibid. 8:24). This explains why this portion of Scripture begins with the words When Pharaoh had let the people go. What was his reward for doing so? Thou shalt not abhor an Egyptian (Deut. 23:8), for the mouth that had said: I know not the Lord (Exod. 5:2) reversed itself and declared: The Lord is righteous (ibid. 9:27). What was his reward for saying this? He gave them a burial place, as it is said: Thou stretchest out Thy right hand—the earth swallowed them (ibid. 15:12).

(Fol. 17) R. Akiba lectured: "If man and wife have merits then the Shechina will dwell among them, but if they have no merits a fire [of dissention] will consume them." Said Raba: "And the [fire of the woman] is even greater than that of the man, because the woman's name (Esha) originally consists of the word fire, (Esh) while in that of the husband (Ish) there is a letter (Yud) which intervenes between the word fire (Esh)." Raba said: "Why did the Torah command to bring dust for a Sota? This is explained that if one has merits, he will have children like Abraham our patriarch, concerning whom it is written (Gen. 18, 27) Although I am but dust and ashes, but if one has no merits, they will bring him to ashes; (i.e., will be burned)."

And the Lord went before them (Exod. 13:21). Just as a man treats other men, so is he treated. Because Abraham escorted the ministering angels, as it is said: And Abraham went with them to bring them on the way (Gen. 18:16), the Holy One, blessed be He, accompanied his sons in the wilderness for forty years. And because Abraham said: Let now a little water be fetched (ibid., v. 4), as is written in the portion And He appeared unto him (Gen. 18:1), the Holy One, blessed be He, caused the well to appear for his children.