Sahih Bukhari
To make the Heart Tender (Ar-Riqaq)
Volume: 008 / Book Number: 076 / Hadith Number: 579
Narrated Ibn 'Umar:
The Prophet said, "There will be a tank (Lake-Fount) in front of you as large as the distance between Jarba and Adhruh (two towns in Sham)."