Al-Mu'jam al-Awsat 34 — he said: Good treatment of relatives

It is narrated from Sayyiduna Abu al-Darda' (may Allah be pleased with him) that he said: "Good treatment of relatives (maintaining ties of kinship) was mentioned in the presence of the Messenger of Allah (peace and blessings be upon him), and we said that whoever maintains ties of kinship has his life extended. At this he (peace and blessings be upon him) said: 'Indeed his lifespan is not (actually) increased, for Allah Almighty says: "Then when their appointed time comes, they cannot delay it by a single hour, nor can they advance it." Rather, it means that a person has righteous offspring who supplicate for him after him, and that (the supplications and their reward) keeps reaching him; this is the way in which his life (in remembrance and reward) is extended.'"
This hadith is narrated from Sayyiduna Abu al-Darda' (may Allah be pleased with him) only with this chain, and Sulayman bin Ata (may Allah have mercy on him) is alone in narrating it.