وَعَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «يَمِينُكَ عَلَى مَا يُصَدِّقُكَ عَلَيْهِ صَاحبك» . رَوَاهُ مُسلم
He reported God’s Messenger as saying, "Your oath should be about something regarding which your companion will believe you.” Muslim transmitted it.
Source: Mishkat al-Masabih — repository translation · Al-Khatib Al-Tabrizi — authenticity/grade metadata requires independent source review · Sunnah.comAudio not available for the selected reciter.
Source: Mishkat al-Masabih — repository arabic · Al-Khatib Al-Tabrizi · Sunnah.com