Sayyiduna Wahshi bin Harb (may Allah be pleased with him) narrates that Sayyiduna Abu Bakr Siddiq (may Allah be pleased with him) had a special flag prepared in honor of Sayyiduna Khalid bin Walid (may Allah be pleased with him) for fighting against the apostates, and said: I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: The best servant of Allah and the best individual of his tribe is Khalid bin Walid, who is one of the swords of Allah, which Allah has drawn from its sheath against the disbelievers and hypocrites.
Hadith Referenceمسند احمد / مسند الخلفاء الراشدين / 43
Hadith Gradingحکم دارالسلام:حديث صحيح بشواهده، وهذا إسناد ضعيف، حرب بن وحشي لم يرو عنه غير ابنه وحشي، فهو مجهول فى الرواية وإن كان معروفاً فى النسب