Musannaf Ibn Abi Shayba 22:28

Shababa narrated to us, from Layth ibn Sa'd, from Ibn Shihab, from 'Abd al-Rahman ibn Ka'b ibn Malik, that the Prophet, may Allah bless him and grant him peace, said to Abu Musa—and he heard him reciting the Qur'an—: "Your brother has indeed been given [a portion] of the flutes of the family of David."