Allah's Apostle said, "May Allah's mercy be on him who is lenient in his buying, selling, and in demanding back his money."
Sahih Bukhari: Volume 3, Book 34, Number 290
I heard Allah's Apostle saying, "whoever desires an expansion in his sustenance and age, should keep good relations with his Kith and kin.
Sahih Bukhari: Volume 3, Book 34, Number 281