In fulfilment of her vow, Hannah handed her young son Samuel over to work for God for his whole life. On that day, Hannah prayed, and as the Holy Spirit came upon her, she began to speak one of the greatest prophecies in the Bible, declaring how God would completely change her nation's situation and send his Anointed King, the Messiah.
Hannah's prophecy was the inspiration behind the great song of Mary, the mother of Jesus, that is called the Magnificat (Luke 1:46-55)