Sahih Muslim
The Book Pertaining to Piety and Softening of Hearts (Kitab Al-Zuhd wa Al-Raqaiq)
Book Number: 042 / Hadith Number: 7108
Abu Huraira reported that Allah's Messenger (may peace be upon him) 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.