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 Apostle."

Narrated Ibn Abi Mulaika: Somebody said to Ibn `Abbas, "Can you speak to the chief of the believers Muwaiya, 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) ."