Musnad Abu Ya'la al-Mawsili 155:369

Abu Bakr ibn Abi Shaybah narrated to us, Yahya ibn Zakariya narrated to us, from Abu Malik al-Ashja‘i, from Abu Hazim, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "You will come with bright foreheads and bright limbs from the traces of ablution; a mark for my nation that no one else possesses."