كتاب الزهد والرقائق
55  
The Book of Zuhd and Softening of Hearts
(2)
Chapter: The Virtue Of Treating Widows, The Poor And Orphans Kindly
(2)
باب الإِحْسَانِ إِلَى الأَرْمَلَةِ وَالْمِسْكِينِ وَالْيَتِيمِ
Sahih Muslim 2983

Abu Huraira reported that Allah's Messenger (ﷺ) said:

One who looks after the orphan whether he is his relative or not, I and he would be together in Paradise like this, and Malik (explained it) with the gesture by drawing his index finger and middle finger close together.
حَدَّثَنِي زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا إِسْحَاقُ بْنُ عِيسَى، حَدَّثَنَا مَالِكٌ، عَنْ ثَوْرِ بْنِ زَيْدٍ، الدِّيلِيِّ قَالَ سَمِعْتُ أَبَا الْغَيْثِ، يُحَدِّثُ عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ كَافِلُ الْيَتِيمِ لَهُ أَوْ لِغَيْرِهِ أَنَا وَهُوَ كَهَاتَيْنِ فِي الْجَنَّةِ ‏"‏ ‏.‏ وَأَشَارَ مَالِكٌ بِالسَّبَّابَةِ وَالْوُسْطَى ‏.‏
Reference : Sahih Muslim 2983
In-book reference : Book 55, Hadith 52
USC-MSA web (English) reference : Book 42, Hadith 7108
  (deprecated numbering scheme)