Exodus 12:3

Speak to all the congregation of the children of Israel, saying, In the tenth of this month, whose time is appointed for this time (occasion), and not for (coming) generations, they shall take to them a lamb for the house of a family, and, if many in number, they shall take a lamb for a house:

THEY SHALL TAKE TO THEM EVERY MAN A LAMB, ACCORDING TO THEIR FATHERS’ HOUSES. The reason for this commandment is that the constellation of Aries (the Ram) is at the height of its power in the month of Nisan, it being the sign of the zodiac which ascends the heavens. Therefore He commanded us to slaughter the sheep and to eat it in order to inform us that it was not by the power of that constellation that we went out from Egypt, but by decree of the Supreme One. And according to the opinion of our Rabbis, etc., (above, 8:22), Onkelos translated: “if we sacrifice that which the Egyptians worship.” In his Moreh Nebuchim (III, 46), Rambam also writes: “Scripture tells us, according to the version of Onkelos, that the Egyptians worshipped Aries, etc.” that the Egyptians worshipped it as a deity, He has all the more informed us through this that He subdued their gods and their powers at the height of their ascendancy. And thus the Rabbis have said: “Take you lambs and slaughter the gods of Egypt.”

לבית אבות, members of several families residing in the same house were in the habit of taking their meals together. They had to do this as the Passover offering could not be split up and consumed in more than one house. שה לבית, this means it was to be consumed in the same house, as per verse 15.

בעשור לחודש, “on the tenth day of the month;” the acquisition of the Paschal lamb in Egypt had to be made on the tenth of the month. There was a special reason for this. When the firstborn Egyptians saw what the Israelites were doing, they asked them for the reason of this. The Israelites explained that it was an offering to be offered when G–d would skip over the homes of the Israelites when He would slay the Egyptian firstborns as a punishment for their refusing to let the Israelites go. Upon hearing this, the firstborn Egyptians immediately went to the other Egyptians telling them to release the Israelites forthwith, accusing them of responsibility for their death in case they refused. Nonetheless, the other Egyptians refused. In fact, they themselves slew some of the firstborns in an altercation. This is what is meant when we read in Psalms 136,10: למכה מצרים בבכוריהם כי לעולם חסדו, i.e. the psalmist does not write: that G–d smote the Egyptian firstborns, but that the Egyptians killed their firstborn. (Compare Midrash Tehillim 136, as well as Yalkut Shimoni on that verse.) We read also in that Midrash that the tenth of the month of Nissan of that year occurred on a Sabbath so that Passover occurred on the Thursday following, as stated in the Talmud, tractate Shabbat folio 87. When the Egyptians saw how the Jews made ready to cut the throats of their lambs they attacked them, as they were afraid of these animals, which were deities for them, and feared punishment for allowing their deities to be slain. G–d performed a miracle for the Israelites thus attacked and they were saved. This is the reason why the Sabbath prior to the Exodus is called שבת הגדול, “the great Sabbath.” Still we need to explore the reason why the tenth day in Nissan was chosen for the command to the Israelites to purchase, or if they had animals to set aside the respective animal for that sacrifice. According to Rashi, the Israelites were required to perform circumcision on themselves prior to being able to slaughter and to partake of the Paschal lamb. It would take them four days to recover from the wounds inflicted through their having circumcised themselves. (Attributed to Rabbi Yitzchok from Ibro.)