Musannaf Ibn Abi Shayba 36:485

Ibn Idris narrated to us, from his father, from Simak, from Alqama bin Wa'il, from Al-Mughira bin Shu'ba, who said: The Messenger of Allah (may Allah bless him and grant him peace) sent me to Najran. They said to me: "You recite, 'O sister of Aaron,' while there was between Moses and Jesus as many years as Allah willed." I did not know what to answer them with, until I returned to the Prophet (may Allah bless him and grant him peace) and asked him. He said: "Did you not inform them that they used to name [their children] after their prophets and the righteous people who came before them?"