Exodus 34:18-20

New Revised Standard Version Catholic Edition

¹⁸ You shall keep the festival of unleavened bread. Seven days you shall eat unleavened bread, as I commanded you, at the time appointed in the month of Abib; for in the month of Abib you came out from Egypt.

¹⁹ All that first opens the womb is mine, all your male^[a] livestock, the firstborn of cow and sheep. ²⁰ The firstborn of a donkey you shall redeem with a lamb, or if you will not redeem it you shall break its neck. All the firstborn of your sons you shall redeem.

No one shall appear before me empty-handed.