Exodus 23:16, 19

and the feast of harvest, the first-fruits of thy labors, which thou sowest in the field: and the feast of ingathering, at the end of the year, when thou gatherest in thy labors out of the field.

The first of the first-fruits of thy ground thou shalt bring into the house of Jehovah thy God. Thou shalt not boil a kid in its mother’s milk.