Musannaf Ibn Abi Shayba 27:203

Ibn Fudayl narrated to us, from Sulayman al-Taymi, from Sufyan, from Abu Ishaq, from Umara ibn Abd, from Ali, who said: Musa and Harun, peace be upon them, set out, and Shibr and Shubayr set out. They reached a mountain in which there was a couch, and Harun slept upon it, and his soul was taken. Musa returned to his people, and they said: "You killed him, out of envy for his character, or his gentleness," or a word similar to that—the doubt is from Sufyan. He said: "How could I kill him when his sons were with me?" He said: "So they chose seventy men." He said: "They chose ten from every tribe." He said: "And that is His saying: 'And Musa chose from his people seventy men.'" They reached him and said: "Who killed you, O Harun?" He said: "No one killed me, but Allah took my soul." They said: "O Musa, we will not disobey." He said: "Then the tremor seized them." He began to pace right and left, saying: "If You had willed, You could have destroyed them before, and me. Would You destroy us for what the foolish among us have done? It is not but Your trial." He said: "So he supplicated to Allah, and He brought them back to life, and He made them all prophets."