Rashi on Genesis 46:15/רש"י על בראשית מ״ו:ט״ו

1אלה בני לאה ואת דינה בתו THESE ARE THE SONS OF LEAH WITH HIS DAUGHTER DINAH. — Scripture associates the men with the name of Leah and the women with that of Jacob for the reason given the Talmud (Niddah 31a).

2שלשים ושלש THIRTY THREE — But in the enumeration above you will find only thirty-two. The one whose name is omitted is Jochebed who was born “between the walls” just as they entered the border city, as it is said (Numbers 26:59) “Jochebed, the daughter of Levi, whom her mother bore to Levi in Egypt — she was born in Egypt, but she was not conceived in Egypt (Bava Batra 123).