(43) General Behavior (Kitab Al-Adab)
كتاب الأدب
(128) Chapter: A man should begin with his own name when writing a letter
(128) باب فِي الرَّجُلِ يَبْدَأُ بِنَفْسِهِ فِي الْكِتَابِ
Sunan Abi Dawud 5134 

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.

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 ‏.‏
Grade :  Da'if in chain (Al-Albani) ضعيف الإسناد  (الألباني)حكم :
Reference : Sunan Abi Dawud 5134
In-book reference : Book 43, Hadith 362
English translation : Book 42, Hadith 5115