The Prophet ﷺ gave a decision on the basis of an oath and a single witness. Abu Dawud said: Al-Rabi' bin Sulaiman al-Mu'adhdhin told me some additional words in this tradition: Al-Shafi'i told me from 'Abd al-'Aziz. I then mentioned it fo Suhail who said: Rabi'ah told me - and he is reliable in my opinion - that I told him this (tradition) and I do not remember it. 'Abd al-'Aziz said: Suhail suffered from some disease which caused him to lose a little of his intelligence, and he forgot some of his traditions. Thereafter Suhail would narrate traditions from Rabi'ah on the authority of his father.
أَنَّ النَّبِيَّ ﷺ قَضَى بِالْيَمِينِ مَعَ الشَّاهِدِ