Midrash su Salmi 105:25

"And Yosef and his brothers and their entire generation passed away," to teach you that as long as one of them was still alive from the original ones that came down to Egypt, the Egyptians did not enslave the Israelites. "And the children of Israel reproduced and spawned," even though Yosef and his brothers died, their God did not die, instead "the children of Israel reproduced and spawned." Another point: Each one gave birth to six children in one litter, as it says: "And the children of Israel reproduced and spawned ..." Some say: Twelve [children in each litter] as it is written: "reproduced" - two, "spawned" - two, "they were many" - two, "they were massive" - two, "very much" - two, "and the land was filled with them" - two, for a total of twelve. "They were massive," some say: six children in each litter. And don't be incredulous, since the scorpion is one of the crawling creatures, and it gives birth to seventy at a time. Rabbi Natan says, "And the land was filled with them," like a field of reeds. "A new king arose," since the Egyptians saw this, they enacted new decrees upon them. That which is written: "A new king arose," Rav and Shmuel [interpret it]. One says: literally new. The other says: his decrees were new, he established decrees and punishments on them. The rationale of the one that says it was literally a new king, as it is written: "new." The rationale of the one that says it is referring to new decrees, since it is not written: "and he died, and a king was anointed." "Who did not know Yosef" -- according to the one who said it was a new king, this makes sense. According to the one who said he established new decrees, how does he explain ["that did not know Yosef"]? That he was _like_ one who did not know Yosef at all. The Rabbis say: Why does it call him a "new king"? Wasn't this the same Pharaoh as before? But the Egyptians said to Pharaoh: "let us mix it up with this nation." He said to them: "You are crazy! Until now we have eaten only because of them; how can we mix it up with them?! Were it not for Yosef we would all be dead." When he didn't listen to them, they deposed him from the throne for three months, until he said to them: "Whatever you want to do I am with you," and they re-appointed him. That is why it says, "A new king arose." The Rabbis took their opening text from this verse (Hosea 5:7): "Against God they have rebelled since they have given birth to foreign children, now the new moon will consume their parts." To teach you that when Yosef died they stopped performing circumcision; they said: Let us be like the Egyptians. From this you learn that Moshe circumcised them on their leaving Egypt. And when they did this [stopped observing circumcision], God converted the love of the Egyptians for them into hatred, as it says (Psalms 105:25): "He changed their mind to hate his nation, to harass his servants", to fulfill the verse (Hosea 5:7): "Now the new moon will consume their parts" [translator's note: the word "new moon," "hodesh," is re-vocalized by the Midrash to the word "new," "hadash."]. "A new king," since he arose and enacted new decrees against them. "Who did not know Yosef," and did he really not know Yosef?! Rabbi Abin said: It is like a parable of one who stoned to death the king's friend. The king said, Cut off his head, for tomorrow he will do the same thing to me. therefore Scripture says of him [Pharaoh] - in other words: today, "he did know Yosef," tomorrow, he will say (Exod. 5:2): "I do not know Adonai."

The prophet said: They have dealt treacherously against the Lord, for they have begotten strange children; now shall the new moon devour them with their portions (Hos. 5:7). That is to say, they gave birth to children, but neglected to circumcise them. This teaches us that after Joseph’s death the people disregarded the covenant of circumcision, saying: Let us be like the Egyptians. When the Holy One, blessed be He, observed this, He suppressed the love He bore them, as it is said: He turned their heart to hate His people (Ps. 125:22).