Musnad Ahmad 788:56

'Affan narrated to us, Shu'bah narrated to us, from 'Awf, from Khalid al-Ahdab, from Safwan ibn Muhriz, who said: Abu Musa fainted, so they wept over him. When he regained consciousness, he said: "I dissociate myself from those whom the Messenger of Allah (peace and blessings of Allah be upon him) dissociated himself from: those who shave (their heads in grief), or tear (their garments), or wail (loudly)."