كتاب التوبة
50
The Book of Repentance
(4)
Chapter: The Vastaess Of Allah's Mercy, Which Prevails Over His Wrath
(4)
باب فِي سَعَةِ رَحْمَةِ اللَّهِ تَعَالَى وَأَنَّهَا سَبَقَتْ غَضَبَهُ ‏‏

Abu Huraira reported Allah's Messenger (ﷺ) 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 animals 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 ninety nine parts of mercy with which He would treat His servants on the Day of Resurrection.
حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ نُمَيْرٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا عَبْدُ الْمَلِكِ، عَنْ عَطَاءٍ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ إِنَّ لِلَّهِ مِائَةَ رَحْمَةٍ أَنْزَلَ مِنْهَا رَحْمَةً وَاحِدَةً بَيْنَ الْجِنِّ وَالإِنْسِ وَالْبَهَائِمِ وَالْهَوَامِّ فَبِهَا يَتَعَاطَفُونَ وَبِهَا يَتَرَاحَمُونَ وَبِهَا تَعْطِفُ الْوَحْشُ عَلَى وَلَدِهَا وَأَخَّرَ اللَّهُ تِسْعًا وَتِسْعِينَ رَحْمَةً يَرْحَمُ بِهَا عِبَادَهُ يَوْمَ الْقِيَامَةِ ‏"‏ ‏.‏
Reference : Sahih Muslim 2752 c
In-book reference : Book 50, Hadith 22
USC-MSA web (English) reference : Book 37, Hadith 6631
  (deprecated numbering scheme)