Gabriel is mentioned in the Bible - once in the Old Testament and once in the New. In the Old Testament, he appears to the prophet Daniel, delivering explanations of Daniel's visions (Daniel 8:15–26, 9:21–27). In the Gospel of Luke, Gabriel appears to the virgin Mary and to Zechariah, foretelling the births of Jesus and John the Baptist, respectively (Luke 1:11–38). In Islam, Gabriel (Jibra'il) is believed to have been the angel who revealed the Qu'ran to the Prophet Muhammad over a period of 23 years.