Exodus 23:19 in the King James Version
The first of the firstfruits of thy land thou shalt bring into the house of the LORD thy God. Thou shalt not seethe a kid in his mother’s milk.
Context
18 “You shall not offer the blood of my sacrifice with leavened bread. The fat of my feast shall not remain all night until the morning.
19 You shall bring the first of the first fruits of your ground into the house of the LORD your God. “You shall not boil a young goat in its mother’s milk.
20 “Behold, I send an angel before you, to keep you by the way, and to bring you into the place which I have prepared.