1 Samuel 1:10-11

She, greatly distressed, prayed to the LORD and wept bitterly. She made a vow and said, “O LORD of hosts, if You will indeed look on the affliction of Your maidservant and remember me, and not forget Your maidservant, but will give Your maidservant a son, then I will give him to the LORD all the days of his life, and a razor shall never come on his head.”