Sahih al-Bukhari 3765
Narrated Ibn Abi Mulaika:
Somebody said to Ibn `Abbas, "Can you speak to the chief of the believers Mu`awiyah, as he does not 
pray except one rak`a as witr?" Ibn `Abbas replied, "He is a Faqih (i.e. a learned man who can give 
religious verdicts) ."
حَدَّثَنَا ابْنُ أَبِي مَرْيَمَ، حَدَّثَنَا نَافِعُ بْنُ عُمَرَ، حَدَّثَنِي ابْنُ أَبِي مُلَيْكَةَ، قِيلَ لاِبْنِ عَبَّاسٍ هَلْ لَكَ فِي أَمِيرِ الْمُؤْمِنِينَ مُعَاوِيَةَ، فَإِنَّهُ مَا أَوْتَرَ إِلاَّ بِوَاحِدَةٍ‏.‏ قَالَ إِنَّهُ فَقِيهٌ‏.‏