Sahih Bukhari | Volume 8 | Hadith Number 438
Narrated by Qais
I heard Khabbab, who had branded his abdomen with seven brands, saying, "Had Allah's Apostle not forbidden us to invoke Allah for death, I would have invoked Allah for death. The companions of Muhammad have left this world without taking anything of their reward in it (i.e., they will have perfect reward in the Hereafter), but we have collected of the worldly wealth what we cannot spend but on earth (i.e. on building houses)."