Sahih Bukhari Volume 8, Book 73, Hadith Number 29.

Narated By Abu Huraira : I heard Allah’s Apostle saying, Allah divided Mercy into one-hundred parts and He kept its ninety-nine parts with Him and sent down its one part on the earth, and because of that, it’s one single part, His creations are Merciful to each other, so that even the mare lifts up its hoofs away from its baby animal, lest it should trample on it.”