Exodus 23:19-21 King James Version (KJV)
19 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.
20 Behold, I send an Angel before thee, to keep thee in the way, and to bring thee into the place which I have prepared.
21 Beware of him, and obey his voice, provoke him not; for he will not pardon your transgressions: for my name is in him.