It was narrated from Sahl bin Sa'd that:
The Messenger of Allah said: "This goodness contains many treasures, and for those there are keys. So glad tidings to the one whom Allah makes a key to good and a lock for evil, and woe to the one whom Allah makes a key to evil and a lock to good." (IT)
English reference (IT): Vol. 1, Book 1, Hadith 238 (IT)
Arabic reference (IT): Book 1, Hadith 244 (IT)