(6) بَابُ إِذَا اخْتَلَفَ الرَّاهِنُ وَالْمُرْتَهِنُ وَنَحْوُهُ فَالْبَيِّنَةُ عَلَى الْمُدَّعِي وَالْيَمِينُ عَلَى الْمُدَّعَى عَلَيْهِ
Narrated Ibn Abu Mulaika:
I wrote a letter to Ibn `Abbas and he wrote to me that the Prophet (ﷺ) had given the verdict that the defendant had to take an oath.
Reference: Sahih al-Bukhari 2514
In-book reference: Book 48, Hadith 7
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 45, Hadith 691