Midras Keluaran 9:27: Mekhilta DeRabbi Yishmael, Midrash Tanchuma Buber, Shemot Rabbah & Mekhilta DeRabbi Shimon Ben Yochai

(Exodus 13:17) "And it was, when G–d sent ("shalach") the people": "sending" in all places is accompaniment, viz. (Genesis 18:16) "And Abraham went with them to send them," (Ibid. 26:31) "And Israel sent them." The mouth (of Pharaoh) that said (Exodus 5:2) "Israel, too, I will not send," it is that (mouth) which said (Ibid. 10:10) "I will send you and your children." How was he rewarded for this? (Devarim 23:8) "You shall not abominate an Egyptian." The mouth which said (Exodus 5:2) "I do not know the L–rd," it is that (mouth) which said (Ibid. 14:25) "I will flee from before Israel, for the L–rd wars for them against the Egyptians." How was he rewarded for this? (Isaiah 19:19) "On that day there will be an altar to the L–rd in the midst of the land of Egypt and a pillar at its border to the L–rd." The mouth which said (Exodus 5:2) "Who is the L–rd that I should hearken to His voice," it is that mouth which said (Ibid. 9:27) "the L–rd is the Tzaddik, and I and my people are the wicked" — wherefore He gave them a place for burial, as it is written (Ibid. 15:12) "You inclined Your right hand — the earth swallowed them up."

(Ps. 66:3, cont.:) AT YOUR GREAT STRENGTH <YOUR ENEMIES> SHALL DWINDLE AWAY (or BE DECEITFUL) (yekhahashu, rt. KHSh)²The Hebrew verb can have either meaning. BEFORE YOU. R. Berekhyah and R. Judah b. R. Shallum the Levite differed. One said: THEY DWINDLE AWAY (yekhahashu) BEFORE YOU, <i.e.,> they shall be broken, just as it is stated (in Deut. 33:29): YOUR ENEMIES SHALL DWINDLE AWAY (yekhahashu) BEFORE YOU. But the other said: THEY ARE DECEITFUL (rt.: KHSh) BEFORE YOU, <i.e.,> your enemies shall lie and act deceitfully (rt.: KHSh). Nebuchadnezzar said (in Dan. 3:28): BLESSED BE THE GOD OF SHADRACH, MESHACH, AND ABED-NEGO, <WHO SENT HIS ANGEL TO DELIVER HIS SERVANTS THAT TRUSTED IN HIM AND FLOUTED THE KING'S DECREE>…. Ergo (in Ps. 66:3): <YOUR ENEMIES> SHALL BE DECEITFUL BEFORE YOU. Sennacherib said (in II Kings 18:35): WHO AMONG ALL THE GODS OF <THOSE> LANDS <HAVE DELIVERED THEIR LAND FROM MY HAND>…? He did not move from there until he had dwindled away, as stated (in II Chron. 32:21): <THEN THE LORD SENT AN ANGEL, WHO DESTROYED EVERY MIGHTY WARRIOR, COMMANDER, AND OFFICER IN THE CAMP OF THE KING OF ASSYRIA. > SO HE RETURNED SHAME [FACED TO HIS OWN LAND]. Pharaoh said (in Exod. 5:2): I DO NOT KNOW THE LORD, <AND MOREOVER I WILL NOT LET ISRAEL GO>. <That statement> became a lie (KHSh) for them, when <Pharaoh> said (in Exod. 9:27): THE LORD IS RIGHT, AND I AND MY PEOPLE ARE IN THE WRONG. So he himself sent them away, as stated (in Exod. 13:17): NOW IT CAME TO PASS, WHEN PHARAOH HAD LET < THE PEOPLE > GO….

Another interpretation (of Exod. 5:2): WHO IS THE LORD? The Holy One said to him: You have said: Who (MY)? By your life, through <the letters> MY you shall be punished (in Exod. 14:26–15:21). MY (who) is YM (sea) in reverse order. Through the sea (YM) you shall know who (MY) I am, because you said (in Exod. 5:2): I DO NOT KNOW THE LORD.²²So Mekhilta de Rabbi Ishmael, Shirata 1, with reference to Exod. 15:4. By your life, some day soon²³Literally: “tomorrow.” you shall say (in Exod. 9:27): THE LORD IS IN THE RIGHT, AND I AND MY PEOPLE ARE IN THE WRONG.²⁴Mekhilta de Rabbi Ishmael, Beshallah 1. You said (in Exod. 5:2): AND MOREOVER I WILL NOT LET ISRAEL GO. By your life, some day soon you shall take each and every one of them by the hand to send them away. It is therefore stated (in Exod. 13:17): [NOW IT CAME TO PASS, WHEN PHARAOH HAD LET THE PEOPLE GO.]