Exodus 23:15-18

15You shall keep the Feast of Unleavened Bread (you shall eat unleavened bread seven days, as I commanded you, at the time appointed in the month of Abib, for in it you came out of Egypt; none shall appear before Me empty);

16and the Feast of Harvest, the firstfruits of your labors which you have sown in the field; and the Feast of Ingathering at the end of the year, when you have gathered in the fruit of your labors from the field.

17“Three times in the year all your males shall appear before the Lord God.

18“You shall not offer the blood of My sacrifice with leavened bread; nor shall the fat of My sacrifice remain until morning.