Companions of the Prophet
حَدَّثَنَا الْحَسَنُ بْنُ بِشْرٍ، حَدَّثَنَا الْمُعَافَى، عَنْ عُثْمَانَ بْنِ الأَسْوَدِ، عَنِ ابْنِ أَبِي مُلَيْكَةَ، قَالَ أَوْتَرَ مُعَاوِيَةُ بَعْدَ الْعِشَاءِ بِرَكْعَةٍ وَعِنْدَهُ مَوْلًى لاِبْنِ عَبَّاسٍ، فَأَتَى ابْنَ عَبَّاسٍ فَقَالَ دَعْهُ، فَإِنَّهُ صَحِبَ رَسُولَ اللَّهِ صلى الله عليه وسلم.Narrated Ibn Abu Mulaika:Muawiya offered one rak`a witr prayer after the `Isha prayer, and at that time a freed slave of Ibn `Abbas was present. He (i.e. the slave) went to Ibn `Abbas (and told him that Muawiya offered one rak`a witr prayer). Ibn `Abbas said, "Leave him, for he was in the company of Allah's Messenger (ﷺ)
Noch nicht in deutscher Übersetzung verfügbar, daher auf Englisch.
Aus Sahih al-Bukhari, dessen Überlieferungen die Gelehrten als authentisch annehmen.