Jabir b. Abdullah reported that Allah's Messenger (ﷺ) said:
He who climbed this hill, the hill of Murar, his sins would be obliterated as were obliterated the sins of Bani Isra'il. So the first to take their horses were the people of Banu Khazraj. Then there was a ceaseless flow of persons and Allah's Messenger (ﷺ) said to them: All of you are those who have been pardoned except the owner of a red camel. We came to him and said to him: You also come on, so that Allah's Messenger (ﷺ) may seek forgiveness for you. But he said: By Allah, so far as I am concerned, the finding of something lost is dearer to me than seeking of forgiveness for me by your companion (the Holy Prophet), and he remained busy in finding out his lost thing.
Reference: Sahih Muslim 2780 a
In-book reference: Book 51, Hadith 15
USC-MSA web (English) reference(deprecated numbering scheme): Book 38, Hadith 6691