Exodus 34:20 in the World English Bible
You shall redeem the firstborn of a donkey with a lamb. If you will not redeem it, then you shall break its neck. You shall redeem all the firstborn of your sons. No one shall appear before me empty.
Context
19 All that openeth the matrix is mine; and every firstling among thy cattle, whether ox or sheep, that is male.
20 But the firstling of an ass thou shalt redeem with a lamb: and if thou redeem him not, then shalt thou break his neck. All the firstborn of thy sons thou shalt redeem. And none shall appear before me empty.
21 Six days thou shalt work, but on the seventh day thou shalt rest: in earing time and in harvest thou shalt rest.