The Book of Virtue, Enjoining Good Manners, and Joining of the Ties of Kinship
حَدَّثَنِي حَرْمَلَةُ بْنُ يَحْيَى التُّجِيبِيُّ، أَخْبَرَنَا ابْنُ وَهْبٍ، أَخْبَرَنِي يُونُسُ، عَنِ ابْنِ شِهَابٍ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ " مَنْ سَرَّهُ أَنْ يُبْسَطَ عَلَيْهِ رِزْقُهُ أَوْ يُنْسَأَ فِي أَثَرِهِ فَلْيَصِلْ رَحِمَهُ " .Anas b. Malik reported:I heard Allah's Messenger (ﷺ) as saying: He who is desirous that his means of sustenance should be expanded for him or his age may be lengthened, should join the tie of relationship
From Sahih Muslim, whose reports the scholars accept as authentic.