1 Samuel 14:24, 28

Now the men of Israel were pressed to exhaustion that day, because Saul had placed them under an oath, saying, “Let a curse fall on anyone who eats before evening—before I have full revenge on my enemies.” So no one ate anything all day

But one of the men saw him and said, “Your father made the army take a strict oath that anyone who eats food today will be cursed. That is why everyone is weary and faint.”