Exodus 22:29

So shalt thou do with thy calf and thy sheep and thine ass; seven days shall it be under the mother, and the eighth day thou shalt give it to me.

You shall not keep back the first fruits of your threshing floor and press. The firstborn of your sons you shall give to me.

Thou shalt not delay to offer the first of thy ripe fruits, and of thy liquors: the firstborn of thy sons shalt thou give unto me.