1 Samuel 14:24, 28

The men of Israel were miserable that day because Saul had made an oath for all of them. He had said, “No one should eat food before evening and before I finish defeating my enemies. If he does, he will be cursed!” So no Israelite soldier ate food.

Then one of the soldiers told Jonathan, “Your father made an oath for all the soldiers. He said any man who eats today will be cursed! That’s why they are so weak.”