'Commandment of the Lord' in the Bible

Samuel said to Saul, “You have acted foolishly; you have not kept the commandment of the Lord your God, which He commanded you, for [if you had obeyed] the Lord would have established your kingdom over Israel forever.

Then Saul said to Samuel, “I have sinned; for I have transgressed the command of the Lord and your words, because I feared the people and obeyed their voice.