I Samuel 1:11, 24-28

Then 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 male child, then I will give him to the LORD all the days of his life, and no razor shall come upon his head.”

Now when she had weaned him, she took him up with her, with three bulls, one ephah of flour, and a skin of wine, and brought him to the house of the LORD in Shiloh. And the child was young. Then they slaughtered a bull, and brought the child to Eli. And she said, “O my lord! As your soul lives, my lord, I am the woman who stood by you here, praying to the LORD. For this child I prayed, and the LORD has granted me my petition which I asked of Him. Therefore I also have lent him to the LORD; as long as he lives he shall be lent to the LORD.” So they worshiped the LORD there.