1 Samuel 13:2
Saul chose him three thousand men of Israel; whereof two thousand were with Saul in Michmash and in mount Beth-el, and a thousand were with Jonathan in Gibeah of Benjamin: and the rest of the people he sent every man to his tent. Saul chose him three thousand men of Israel; whereof two thousand were with Saul in Michmash and in mount Beth-el, and a thousand were with Jonathan in Gibeah of Benjamin: and the rest of the people he sent every man to his tent.
After the victory over the Ammonites, Saul sent most of Israel's army home to their tents and kept three thousand men for himself. Two thousand of these were stationed with Saul himself at Michmash and Mount Bethel, and one thousand were placed with Jonathan at Gibeah of Benjamin. Disbanding most of the army at that moment was a serious mistake, for the people were encouraged by victory and an immediate attack upon other enemies could have advanced Israel's freedom.
In that same setting Saul later came under severe pressure from the Philistines while his own troops were scattering from him. Because Samuel had not arrived by the appointed time, Saul himself offered a burnt offering. He acted from impatience, and in doing so he violated God's command that only those consecrated to the priestly office should offer sacrifices. Samuel rebuked him for failing to keep God's command and declared that his kingdom would not continue, though God would have established his kingdom over Israel forever if he had obeyed.