حَدَّثَنَا مُحَمَّدُ بْنُ عِيسَى، حَدَّثَنَا الْحَارِثُ بْنُ مُرَّةَ، حَدَّثَنَا كُلَيْبُ بْنُ مَنْفَعَةَ، عَنْ جَدِّهِ، أَنَّهُ أَتَى النَّبِيَّ صلى الله عليه وسلم فَقَالَ يَا رَسُولَ اللَّهِ مَنْ أَبَرُّ قَالَ ‏"‏ أُمَّكَ وَأَبَاكَ وَأُخْتَكَ وَأَخَاكَ وَمَوْلاَكَ الَّذِي يَلِي ذَاكَ حَقٌّ وَاجِبٌ وَرَحِمٌ مَوْصُولَةٌ ‏"‏ ‏.‏

Kulaib b. Manfa'ah said that his grandfather told then he went to the Prophet (PBUH) and said: Messenger of Allah! to whom should I show kindness? He said: Your mother, your sister, your brother and the slave whom you set free and who is your relative, a due binding (on you), and a tie of relationship which should be joined. Translation Not Available

Book Ref: Sunan Abi Dawud Book 43 Hadith 5140
Web Ref:  Sunan Abi Dawud Book 42 Hadith 5121