Комментарий к Бамидбар 29:32

וביום השביעי פרים עשרה, “and on the seventh day, ten young bullocks.” The total number of young bullocks offered on the seven days of Sukkot was seventy. This corresponded to the fifty two Sabbath days in the year, seven days of Passover, one day of Shavuot, one day of New Year, one day of Atonement, and eight days of Sukkot/Sh’mini Atzeret. According to Rashi.