1 Samuel 13:9-10
9-10So Saul took charge: "Bring me the burnt offering and the peace offerings!" He went ahead and sacrificed the burnt offering. No sooner had he done it than Samuel showed up! Saul greeted him.
11-12Samuel said, "What on earth are you doing?"
Saul answered, "When I saw I was losing my army from under me, and that you hadn't come when you said you would, and that the Philistines were poised at Micmash, I said, 'The Philistines are about to come down on me in Gilgal, and I haven't yet come before God asking for his help.' So I took things into my own hands, and sacrificed the burnt offering."