Saul’s mistake was in assuming that he had the authority to set aside God’s revealed will because time was of the essence. He was losing the confidence of the people because Samuel delayed. So, he decided to sidestep Samuel as anointed priest, and do the sacrifice himself.
Unbelievers are guilty of the same thing when they try to win God’s favor with their own good works, essentially side-stepping Jesus as God’s anointed Savior. Saul was rejected as king for that blunder.
LORD, we accept your solution to our sin problem – Jesus Christ. We will wait for him to deliver us.