Exodus 34:18-20

Revised Standard Version

¹⁸ “The feast of unleavened bread you shall keep. Seven days you shall eat unleavened bread, as I commanded you, at the time appointed in the month Abib; for in the month Abib you came out from Egypt. ¹⁹ All that opens the womb is mine, all your male^[a] cattle, the firstlings of cow and sheep. ²⁰ The firstling of an ass you shall redeem with a lamb, or if you will not redeem it you shall break its neck. All the first-born of your sons you shall redeem. And none shall appear before me empty.