Musnad Ahmad 31:541

'Affan narrated to us, Hammad narrated to us, from 'Asim ibn Bahdalah, from Abu Salih, from Abu Hurairah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Allah has one hundred mercies. He has ninety-nine with Him, and He placed one among you, by which you show mercy to one another among the jinn and mankind, and among the creation. So when the Day of Resurrection comes, He will add it to them."