“Its chain of transmission consists of trustworthy narrators.”
Al-Mundhirī likewise said so in al-Targhīb (1/160), but he deemed it defective on account of a break between Abū Ayyūb and Ibn ʿAmr. There is no basis for this. And Allah knows best.
It also has another route, which Aḥmad (2/208) transmitted from ʿAlī ibn Zayd, from Muṭarrif ibn ʿAbdullāh ibn al-Shikhkhīr, from ʿAbdullāh ibn ʿAmr, with the same wording. This chain is acceptable for corroboration. All its narrators are trustworthy except ʿAlī ibn Zayd—namely, Ibn Judʿān—who is somewhat weak due to his poor memory.
662 — “Those who emigrated have taken all its reward.”
Al-Ṭaḥāwī, in Mushkil al-Āthār (3/252), and al-Ḥākim (3/316) transmitted it through two routes from Zuhayr ibn Muʿāwiyah, who said: ʿĀṣim al-Aḥwal narrated to us from Abū ʿUthmān al-Nahdī, who said: Mujāshiʿ ibn Masʿūd narrated to us, saying: “After the Conquest, I came to the Messenger of Allah (peace and blessings be upon him) with my brother Mujālid and said: ‘O Messenger of Allah, I have brought you my brother Mujālid so that he may pledge allegiance to you for emigration.’ He replied”—and then mentioned the preceding statement. I said: “Then upon what will you accept his pledge of allegiance, O Messenger of Allah?” He said: “I will accept his pledge upon Islam, faith, and jihad.”
This is al-Ḥākim’s wording, and neither he nor al-Dhahabī commented on it. Al-Ṭaḥāwī added: “He said: Later, I met Maʿbad—who was the elder of the two—and asked him. He replied: ‘Mujāshiʿ spoke the truth.’”
I say: Its chain of transmission is authentic.