https://hadithcollection.com/sahihbukhari/sahih-bukhari-book-45-mortgaging/narated-by-ibn-abu-mulaika-i-wrote-a-letter-to-ibn-abbas-and-he-wrote-to-me-that-the-prophet-had-given-the-verdict-that-the-defendant-had-to-take-an-oath
Sahih Bukhari Volume 3, Book 45, Hadith Number 691.