(351) بَابُ قَوْلِ الرَّجُلِ: يَا بُنَيَّ، لِمَنْ أَبُوهُ لَمْ يُدْرِكِ الإسْلامَ
Anas said, "I used to serve the Prophet, may Allah bless him andgrant him peace." He continued, "I used to enter without asking for permissionto enter. One day I came and he said, 'My son, there is a new situation.You should not come in unless you have permission.'"
Reference: Al-Adab Al-Mufrad 807
In-book reference: Book 33, Hadith 54
English translation: Book 33, Hadith 807