(493) بَابُ الاسْتِئْذَانُ غَيْرُ السَّلامِ
Regarding the person who asks for permission to enter before hegives the greeting, Abu Hurayra said, "He is not given permission untilhe has first given the greeting."
Reference: Al-Adab Al-Mufrad 1066
In-book reference: Book 43, Hadith 16
English translation: Book 43, Hadith 1066