Al-Kāfi - Volume 7 > One who Does not have Testimony, then Oath is Turned on Him
Hadith #2

2- مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ عِيسَى عَنِ الْحُسَيْنِ بْنِ سَعِيدٍ عَنِ النَّضْرِ بْنِ سُوَيْدٍ عَنِ الْقَاسِمِ بْنِ سُلَيْمَانَ عَنْ عُبَيْدِ بْنِ زُرَارَةَ عَنْ أَبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) فِي الرَّجُلِ يُدَّعَى عَلَيْهِ الْحَقُّ وَلا بَيِّنَةَ لِلْمُدَّعِي قَالَ يُسْتَحْلَفُ أَوْ يَرُدَّ الْيَمِينَ عَلَى صَاحِبِ الْحَقِّ فَإِنْ لَمْ يَفْعَلْ فَلا حَقَّ لَهُ.

2. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad ibn ‘Isa from al-Husayn ibn Sa‘id from al-Nadr ibn Suwayd from al-Qasim ibn Sulayman from ‘Ubayd ibn Zurarah who has narrated the following: “About the case of a man who brings a complaint against another but does not have testimony, abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘He must ask him (defendant) to take an oath, and if he turns the oath on the plaintiff who does not take the oath, then he has no right.’”