Musnad Ahmad 33:705

Hashim narrated to us, Shu'bah narrated to us, Sayyar Abu al-Hakam narrated to us, he said: I heard al-Sha'bi narrating from Jabir ibn Abdullah, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "When one of you enters [his home] at night, let him not come to his wife unexpectedly, so that the woman whose husband has been away may shave her pubic hair, and the woman with disheveled hair may comb it."