Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
bayhaqi:20860Abū ʿAbd al-Raḥman al-Sulamī > Abū al-Ḥasan al-Kārizī > ʿAlī b. ʿAbd al-ʿAzīz > Abū ʿUbayd > Ḥafṣ b. Ghiyāth > Muḥammad b. Zayd b. Muhājir > Ṭalḥah b. ʿAbdullāh b. ʿAwf

[Machine] The Messenger of Allah ﷺ sent a caller until he reached Ath-Thaniyah and said that the testimony of an adversary and a doubtful person is not permissible, and that the oath is upon the defendant.  

البيهقي:٢٠٨٦٠أَخْبَرَنَا أَبُو عَبْدِ الرَّحْمَنِ السُّلَمِيُّ ثنا أَبُو الْحَسَنِ الْكَارِزِيُّ أنبأ عَلِيُّ بْنُ عَبْدِ الْعَزِيزِ عَنْ أَبِي عُبَيْدٍ ثنا حَفْصُ بْنُ غِيَاثٍ عَنْ مُحَمَّدِ بْنِ زَيْدِ بْنِ مُهَاجِرٍ عَنْ طَلْحَةَ بْنِ عَبْدِ اللهِ بْنِ عَوْفٍ

أَنَّ رَسُولَ اللهِ ﷺ بَعَثَ مُنَادِيًا حَتَّى انْتَهَى إِلَى الثَّنِيَّةِ أَنَّهُ لَا تَجُوزُ شَهَادَةُ خَصْمٍ وَلَا ظَنِينٍ وَالْيَمِينُ عَلَى الْمُدَّعَى عَلَيْهِ  

أَخْرَجَهُ أَبُو دَاوُدَ مَعَ حَدِيثِ الْأَعْرَجِ فِي الْمَرَاسِيلِ