BT Beṣ 27b(1) :מאתמל הוה חזי ולמחר שיולי הוה משייל להו‏ : he used to check (for a blemish on a firstborn animal) on the day before (the holiday), and on the next day he would merely inquire about them
See the entire entry for ˀeṯmāl(y) adv. yesterday