Musannaf Ibn Abi Shayba 32:9

Abu Mu'awiyah narrated to us, from al-A'mash, from Abu Salih, from Abu Sa'id, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Indeed, Allah created, on the day He created the heavens and the earth, one hundred mercies. He placed one mercy of them upon the earth; by it, a mother shows affection to her child, and the beasts show affection to one another. And He delayed ninety-nine until the Day of Resurrection. So when the Day of Resurrection comes, He will complete them with this mercy to be one hundred mercies."