Musar sobre Exodo 1:9

I have also told you that these "sparks," i.e. result of these emissions, first surfaced during the generation of the Deluge and the generation of the Tower of Babel. Those generations were similarly remiss. Joseph first circumcised the Egyptians and then transferred them in order to morally refine them. He wanted to repair the damage inflicted on the world through the wasteful seminal emissions by all those generations. He tried to lead those people back to sanctity and the holy covenant by his action. This is the real meaning of Genesis 47,21: ואת העם העביר אותו לערים מקצה גבול מצרים ועד קצהו, "He transferred the people from the cities from one end of Egypt to the other." Joseph had first circumcised the people whom he transferred. The transfer was to refine them morally. In the course of time the mixed multitude that joined the Jewish people at the time of the Exodus were people descended from those whom Joseph had circumcised. This is the mystical dimension of Exodus 1,9: ויאמר אל עמו הנה עם בני ישראל, He said to his people: "Here are the people of the children of Israel, etc." Pharaoh later on referred to the people who became the ערב רב, the fellow travellers.

The Torah refers to the children of Israel twice; once in verse 9, and once in verse 12. Only in the second reference are we told that the Egyptians abhorred the Israelites. The latter reference is to the Jews who were circumcised and who performed slave labour in their own cities while preserving their Jewish way of life, including circumcision. Pharaoh observed another group of people, who, though described as עם בני ישראל, were nonetheless not of Jewish descent. This is why the Torah says: "He said to his (own) people." Although the former (verse 9) group were Egyptians, they did not view themselves as the people of Pharaoh. We are told later of the Egyptians' reaction to the true Jews. This helps to explain the positive function of the exile, namely to collect (in a spiritual sense) the "sparks" of this impurity represented by the seminal emissions which had contributed to making Egypt the ערות הארץ, centre of immorality on earth. This is also one of the deeper reasons for the mixed multitude who joined the Jewish people at the Exodus. Just as it is possible to absorb "sparks" of impurity, it is equally possible to absorb ניצוצות, "sparks" of sanctity. In the case of the mixed multitude, they had absorbed "sparks" of sanctity from the Jewish people and at the right moment this translated into their desire to become part of the Jewish people.