Honor Killing
I think there is some mistake in reference. Reference link gives following hadith having nno link to killing 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).”