Sahih Muslim
The Book Pertaining to Repentance and Exhortation to Repentance (Kitab Al-Tauba)
Book Number: 037 / Hadith Number: 6631
Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: There are one hundred (parts of) mercy for Allah and He has sent down out of these one part of mercy upon the jinn and human beings and the insects and it is because of this (one part) that they love one another, show kindness to one another and even the beast treats its young one with affection, and Allah has reserved ninetynine parts of mercy with which He would treat His servants on the Day of Resurrection.