He said, I heard the Messenger of Allah ﷺ say, "Allah is more delighted at the repentance of His believing servant than a man in a barren, deadly desert who had his mount with him, carrying his food and drink. He slept and woke to find it gone. He searched for it until thirst overcame him, then said, 'I will return to the place where I was and sleep there until I die.' So he laid his head upon his forearm to die. Then he woke up, and there was his mount beside him, carrying his provisions, his food, and his drink. Allah is more delighted at the repentance of His believing servant than this man is at finding his mount and his provisions."
قال سمعت رسول الله ﷺ يقول: الله أشد فرحا بتوبة عبده المؤمن، من رجل في أرض دوية مهلكة، معه راحلته، عليها طعامه وشرابه، فنام فاستيقظ وقد ذهبت، فطلبها حتى أدركه العطش، ثم قال: أرجع إلى مكاني الذي كنت فيه، فأنام حتى أموت، فوضع رأسه على ساعده ليموت، فاستيقظ وعنده راحلته وعليها زاده وطعامه وشرابه، فالله أشد فرحا بتوبة العبد المؤمن من هذا براحلته وزاده.
Bukhari narrated it in the Book of Supplications (6308), and Muslim in the Book of Repentance (2744), both through Amash, from Umara bin Umayr, from Harith bin Suwayd, who said, I visited Abdullah while he was sick, and he told us two hadiths, one from himself and one from the Messenger of Allah ﷺ, and then he mentioned it. The wording given is Muslim's, and Bukhari's wording is similar. His statement "a wilderness land" means a barren land with no vegetation in it.