Exodus 34:26
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. 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.
Exodus 34:26 belongs among the stated requirements in which God makes known what He requires of His people. The requirement specifies the very day to be kept, leaving no room for carelessness or indifference about which day is observed. Observance of the first day of the week finds no excuse in God's Word, which declares the sanctified seventh day to be the Sabbath.