Sahih Muslim , Book 42, Hadith 7108 (USC-MSA) ⓘ
Abu Huraira reported that Allah's Messenger 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 .
also referenced under: Book 55, Hadith 52 (In-Book) & Hadith 2983 (Reference)