On the day Moses comes down from Mount Sinai with the stone tablets containing the Ten Commandments, he discovers that the Israelites have created a golden calf. To punish the people, Moses gathers a group of men and takes the following action.
Exodus - 32
Moses says to the men. "This is what the Lord, the God of Israel, says: 'Each man strap a sword to his side. Go back and forth through the camp from one end to the other, each killing his brother and friend and neighbor.' "
The Levites did as Moses commanded, and that day about three thousand of the people died.
Isn't it ironic one minute we have God carving into a stone tablet, "Thou shalt not kill." Then the next minute we have God telling each man to strap a sword to his side and murder thousands.