Musnad Abu Ya'la al-Mawsili 159:124

Ishaq ibn Abi Isra'il narrated to us, 'Abdah narrated to us, from 'Abd al-Malik, from 'Ata', from Abu Hurayrah, from the Prophet (peace and blessings of Allah be upon him), who said: "Indeed, Allah has one hundred mercies. He sent down one mercy of them among mankind, the jinn, the wild beasts, and the vermin. By it, they show affection to one another, by it they show mercy to one another, and by it, the wild beasts show affection to their offspring. And He has reserved for Himself ninety-nine mercies, with which He will show mercy to His servants on the Day of Resurrection."