To make the Heart Tender (Ar-Riqaq)

Bukhari :: Book 8 :: Volume 76 :: Hadith 452

Narrated Abu Huraira:

Allah Apostle said, "If I had gold equal to the mountain of Uhud, it would not please me that anything of it should remain with me after three nights (i.e., I would spend all of it in Allah's Cause) except what I would keep for repaying debts."