Sahih Muslim , Book 37, Hadith 6629 (USC-MSA)

Abu Huraira reported: I heard Allah's Messenger as saying: Allah created mercy in one hundred parts and He retained with Him ninety-nine parts, and He has sent down upon the earth one part, and it is because of this one part that there is mutual love among the creation so much so that the animal lifts up its hoof from its young one, fearing that it might harm it.

حَدَّثَنَا حَرْمَلَةُ بْنُ يَحْيَى التُّجِيبِيُّ، أَخْبَرَنَا ابْنُ وَهْبٍ، أَخْبَرَنِي يُونُسُ، عَنِ ابْنِ شِهَابٍ، أَنَّ سَعِيدَ بْنَ الْمُسَيَّبِ، أَخْبَرَهُ أَنَّ أَبَا هُرَيْرَةَ قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏ "‏ جَعَلَ اللَّهُ الرَّحْمَةَ مِائَةَ جُزْءٍ فَأَمْسَكَ عِنْدَهُ تِسْعَةً وَتِسْعِينَ وَأَنْزَلَ فِي الأَرْضِ جُزْءًا وَاحِدًا فَمِنْ ذَلِكَ الْجُزْءِ تَتَرَاحَمُ الْخَلاَئِقُ حَتَّى تَرْفَعَ الدَّابَّةُ حَافِرَهَا عَنْ وَلَدِهَا خَشْيَةَ أَنْ تُصِيبَهُ ‏" ‏ ‏.‏

sunnah.com