(497) بَابُ دُعَاءُ الرَّجُلِ إِذْنُهُ
Abu Hurayra reported that the Prophet, may Allah bless him andgrant him peace, said, "A man's messenger to another man is his permissionto enter."
Reference: Al-Adab Al-Mufrad 1076
In-book reference: Book 43, Hadith 26
English translation: Book 43, Hadith 1076