Usamah ibn Zayd has been corroborated in the first route. Al-Tirmidhi narrated it (2/316) through Hisham ibn Saʿd, from Zayd ibn Aslam, from Abu Hurayrah, with the same wording. He said: “It is a good, singular hadith. We do not know of Zayd ibn Aslam having heard from Abu Hurayrah; in my view, it is a mursal hadith.”

I say: Yet its transmission through the first route with a connected chain, as well as through the other routes from Abu Hurayrah, indicates that the hadith has a basis—especially since the words, “a sword among the swords of Allah,” are established in the two Sahihs and elsewhere on the authority of Anas. The hadith also has another corroborating report with the wording: “What an excellent servant of Allah and brother to his tribe Khalid ibn al-Walid is: a sword among the swords of Allah, which Allah has unsheathed against the disbelievers and the hypocrites.” Ahmad (1/8), al-Hakim (3/298), and Ibn ʿAsakir (5/271/1 and 2/17/372/1) narrated it from ʿAli ibn ʿAyyash, who said: Al-Walid ibn Muslim informed us; Wahshi ibn Harb narrated to me from his father, from his grandfather Wahshi ibn Harb, that Abu Bakr commissioned Khalid ibn al-Walid to fight the apostates. He said: He then cited it as a report attributed to the Prophet. Al-Hakim said: “Its chain of transmission is authentic.” Al-Dhahabi made no comment on it.

I say: A number of narrators besides al-Walid ibn Muslim transmitted from Wahshi ibn Harb, and Ibn Hibban declared him trustworthy. Al-Hafiz said: “His reliability was not established.” But his father, Harb ibn Wahshi ibn Harb, is known only through the narration of his son Wahshi; for this reason, al-Bazzar called him unknown. It has another corroborating report from ʿUmar, may Allah be pleased with him, with the wording: “Khalid ibn al-Walid is a sword among the swords of Allah, which He has unsheathed against the polytheists.” Ibn ʿAsakir (5/271/2) narrated it from al-Walid ibn Shujaʿ, who said: Damrah informed us; al-Shaybani informed me from Abu al-ʿAjma, who said: It was said to ʿUmar ibn al-Khattab, “If only you would appoint a successor, O Commander of the Faithful.” He replied: “If Abu ʿUbaydah ibn al-Jarrah were still alive, I would appoint him; then, when I came before my Lord and He asked me, ‘Why did you appoint him as successor over the Ummah of Muhammad?’ I would say: ‘I heard Your servant and close friend say: Every Ummah has a trustee, and the trustee of this Ummah is Abu ʿUbaydah ibn al-Jarrah.’ And if Khalid ibn al-Walid were still alive, I would appoint him; then, when I came before my Lord and He asked me, ‘Whom did you appoint as successor over the Ummah of Muhammad?’ I would say: ‘I heard Your servant and close friend say’”—then he cited the statement. And he said: