1 Samuel 1:11-13

And she made this vow: “O LORD of Heaven’s Armies, if you will look upon my sorrow and answer my prayer and give me a son, then I will give him back to you. He will be yours for his entire lifetime, and as a sign that he has been dedicated to the LORD, his hair will never be cut.” As she was praying to the LORD, Eli watched her. Seeing her lips moving but hearing no sound, he thought she had been drinking.