Ibn ‘Abbas, on being asked whether he approved of the Commander of the Faithful, Mu'awiya, using only one <i>rak'a</i> in the <i>witr</i>, replied, “He is right; he is versed in the law.” In a version Ibn Abu Mulaika said that Mu'awiya observed a <i>witr</i> after the evening prayer with one <i>rak'u</i> 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.

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