سُنَنُ أَبِي دَاوُدَ
Sunan Abi Dawud 5134
General Behavior (Kitab Al-Adab)
A man should begin with his own name when writing a letter
حَدَّثَنَا أَحْمَدُ بْنُ حَنْبَلٍ، حَدَّثَنَا هُشَيْمٌ، عَنْ مَنْصُورٍ، عَنِ ابْنِ سِيرِينَ، - قَالَ أَحْمَدُ قَالَ مَرَّةً يَعْنِي هُشَيْمًا - عَنْ بَعْضِ وَلَدِ الْعَلاَءِ أَنَّ الْعَلاَءَ بْنَ الْحَضْرَمِيِّ كَانَ عَامِلَ النَّبِيِّ صلى الله عليه وسلم عَلَى الْبَحْرَيْنِ فَكَانَ إِذَا كَتَبَ إِلَيْهِ بَدَأَ بِنَفْسِهِ .
Narrated al-Ala' ibn al-Hadrami: Some of the children of al-Ala' ibn al-Hadrami said: Al-Ala' ibn al-Hadrami was the governor of the Prophet (ﷺ) at al-Bahrayn, and when he wrote to him he began with his won name.
Sunan Abi Dawud, 5134Da'if in chain (Al-Albani)ضعيف الإسناد (الألباني)