Musnad Ahmad 5:640

'Abd al-Razzaq narrated to us, Sufyan informed us, from a sheikh of theirs who is called Salim, from 'Abd Allah ibn Mulayl, he said: I heard 'Ali saying: "Every prophet was given seven noble ones from his nation, and the Prophet, may Allah bless him and grant him peace, was given fourteen noble ones from his nation, among them Abu Bakr and 'Umar."