Exodus 34:26 in the King James Version
The first of the firstfruits of thy land thou shalt bring unto the house of the LORD thy God. Thou shalt not seethe a kid in his mother’s milk.
Context
25 “You shall not offer the blood of my sacrifice with leavened bread. The sacrifice of the feast of the Passover shall not be left to the morning.
26 “You shall bring the first of the first fruits of your ground to the house of the LORD your God. “You shall not boil a young goat in its mother’s milk.”
27 The LORD said to Moses, “Write these words; for in accordance with these words I have made a covenant with you and with Israel.”