Sayyiduna Muslim bin al-Harith (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) had a letter written for him, containing a recommendation about him to the rulers who would come after, and had it sealed.
Ahmad recorded it; its narrators are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 16168
Hadith Gradingمحدثین:إسنادہ صحیح
Hadith Takhrij«اخرجه احمد فى المسند (234/4) ، أخرجه مسند أحمد برقم: 17593»