Full Sharh — Mishkat al-Masabih 1209
عَنِ ابْنِ عَبَّاسٍ قِيلَ لَهُ: هَلْ لَكَ فِي أَمِير الْمُؤمنِينَ مُعَاوِيَة فَإِنَّهُ مَا أَوْتَرَ إِلَّا بِوَاحِدَةٍ؟ قَالَ: أَصَابَ إِنَّهُ فَقِيهٌ وَفِي رِوَايَةٍ: قَالَ ابْنُ أَبِي مُلَيْكَةَ: أَوْتَرَ مُعَاوِيَةُ بَعْدَ الْعِشَاءِ بِرَكْعَةٍ وَعِنْدَهُ مَوْلًى لِابْنِ عَبَّاسٍ فَأَتَى ابْنَ عَبَّاسٍ فَأَخْبَرَهُ فَقَالَ: دَعْهُ فَإِنَّهُ قَدْ صَحِبَ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ. رَوَاهُ الْبُخَارِيُّ
English Translation
Ibn ‘Abbas, on being asked whether he approved of the Commander of the Faithful, Mu'awiya, using only one rak'a in the witr, replied, “He is right; he is versed in the law.” In a version Ibn Abu Mulaika said that Mu'awiya observed a witr after the evening prayer with one rak'u when a client of Ibn ‘Abbas was with him. He went to Ibn ‘Abbas and told him, but he replied, “Leave him alone, for he was a companion of the Prophet.” Bukhari transmitted it.
Source
Mishkat al-Masabih(مشكاة المصابيح)
Prayer
Hadith Number
1209