1 Samuel 1:10-12

10While her soul was bitter, she prayed to Adonai and wept.

11So she made a vow and said, “Adonai-Tzva’ot, if You will indeed look upon the affliction of Your handmaid, remember me and not forget Your handmaid, but grant Your handmaid a son, then I will give him to Adonai all the days of his life and no razor will ever touch his head.”

12It came to pass, as she prayed long before Adonai, that Eli was watching her mouth.