رِيَاضُ الصَّالِحِينَ
Riyad as-Salihin 341
The Book of Miscellany
Excellence in doing Good to the Friends of Parents and other Relatives
عَنِ ابْنِ عُمَرَ رَضِيَ اللَّه عَنْهُمَا أَنَّ النَّبِيَّ صَلَّى اللَّه عَلَيْهِ وَسَلَّمَ قَالَ: إِنَّ أَبَرَّ الْبِرِّ أَنْ يَصِلَ الرَّجُلُ ود أبيه .
'Abdullah bin 'Umar (May Allah be pleased with them) reported: The Prophet (ﷺ) said, "The finest act of goodness is that a person should treat kindly the loved ones of his father".
Riyad as-Salihin, 341