Sahih Bukhari
To make the Heart Tender (Ar-Riqaq)
Volume: 008 / Book Number: 076 / Hadith Number: 439
Narrated Qais:
I came to Khabbab while he was building a wall, and he (Khabbab) said, "Our companions who have left this world, did not enjoy anything of their reward therein, while we have collected after them, much wealth that we cannot spend but on earth (i.e., on building)."