Sahih Al Bukhari – Book of Sales And Trade

Volumn 003, Book 034, Hadith Number 281.
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Narated By Anas bin Malik : I heard Allah's Apostle saying, "whoever desires an expansion in his sustenance and age, should keep good relations with his Kith and kin."

what is Sustenance:

1: the financial means whereby one lives;

2:a source of materials to nourish the body; 3:the act of sustaining life by food or providing a means of subsisten

what is kith and kin:  

1. One's acquaintances and relatives.

2. One's relatives.