Al-Adab Al-Mufrad, Book 1, Hadith 42 (English) ⓘ

Sa'd ibn 'Ubada az-Zurqi reported that his father said, "I was sitting in the mosque in Madina with 'Amr ibn 'Uthman when 'Abdullah ibn Salam walked by, leaning on his nephew. 'Amr left the assembly and showed his concern for him." Then Ibn Salam returned to them and said, "Do what you like, 'Amr ibn 'Uthman," (and he said it two or three times) By the One who sent Muhammad, may Allah bless him and grant him peace, with the Truth, it is in the Book of Allah Almighty (and he said it twice), 'Do not cut off those your father has joined so that that extinguishes your light.'"

أَخْبَرَنَا بِشْرُ بْنُ مُحَمَّدٍ، قَالَ‏:‏ أَخْبَرَنَا عَبْدُ اللهِ، قَالَ‏:‏ أَخْبَرَنَا عَبْدُ اللهِ بْنُ لاَحِقٍ قَالَ‏:‏ أَخْبَرَنِي سَعْدُ بْنُ عُبَادَةَ الزُّرَقِيُّ، أَنَّ أَبَاهُ قَالَ‏:‏ كُنْتُ جَالِسًا فِي مَسْجِدِ الْمَدِينَةِ مَعَ عَمْرِو بْنِ عُثْمَانَ، فَمَرَّ بِنَا عَبْدُ اللهِ بْنُ سَلاَّمٍ مُتَّكِئًا عَلَى ابْنِ أَخِيهِ، فَنَفَذَ عَنِ الْمَجْلِسِ، ثُمَّ عَطَفَ عَلَيْهِ، فَرَجَعَ عَلَيْهِمْ فَقَالَ‏:‏ مَا شِئْتَ عَمْرَو بْنَ عُثْمَانَ‏؟‏ مَرَّتَيْنِ أَوْ ثَلاَثًا، فَوَالَّذِي بَعَثَ مُحَمَّدًا صلى الله عليه وسلم بِالْحَقِّ، إِنَّهُ لَفِي كِتَابِ اللهِ عَزَّ وَجَلَّ، مَرَّتَيْنِ‏:‏ لاَ تَقْطَعْ مَنْ كَانَ يَصِلُ أَبَاكَ فَيُطْفَأَ بِذَلِكَ نُورُكَ‏.‏