Exodus 34:26-28 King James Version (KJV)
26 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.
27 And the Lord said unto Moses, Write thou these words: for after the tenor of these words I have made a covenant with thee and with Israel.
28 And he was there with the Lord forty days and forty nights; he did neither eat bread, nor drink water. And he wrote upon the tables the words of the covenant, the ten commandments.