"Or eight or nine." He said: "Will you not pledge allegiance to the Messenger of Allah?" So we extended our hands. A speaker said: "O Messenger of Allah, we have already pledged allegiance to you, so on what shall we pledge allegiance to you now?" He said: "That you worship Allah and associate nothing with Him, establish the five prayers, hear and obey"—and he whispered a hidden word—"and that you do not ask people for anything." He said: "I indeed saw some of those men whose whip fell, and he would not ask anyone to hand it to him." (1)

2868 — Ali ibn Muhammad narrated to us, Waki' narrated to us, Shu'bah narrated to us, from 'Attab, the freed slave of Hurmuz, who said:
I heard Anas ibn Malik say: We pledged allegiance to the Messenger of Allah, peace and blessings be upon him, upon hearing and obedience, and he said: "In whatever you are able." (2)

2869 — Muhammad ibn Rumh narrated to us, al-Layth ibn Sa'd informed us, from Abu al-Zubayr,
from Jabir who said: A slave came and pledged allegiance to the Prophet, peace and blessings be upon him, upon emigration, and the Prophet, peace and blessings be upon him, did not realize that he was a slave. Then his master came seeking him, and the Prophet, peace and blessings be upon him, said: "Sell him to me."

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(1) Authentic hadith. Hisham ibn 'Ammar and al-Walid ibn Muslim are corroborators.
Also narrated by Muslim (1043), Abu Dawud (1642), and al-Nasa'i 1/229 via multiple chains from Sa'id ibn 'Abd al-'Aziz, with this chain.
It is in the "Musnad" of Ahmad (23993), and "Sahih Ibn Hibban" (3385).
(2) Authentic through corroboration, and this chain is good because of 'Attab, the freed slave of Hurmuz, and he has been corroborated.
Also narrated by al-Tayalisi (2083), Ahmad (12203), Abu 'Awanah 4/352, and Abu al-Qasim in "al-Ja'diyyat" (1531) via Shu'bah, with this chain.
Also narrated by Ahmad (13264) and al-Bukhari in his "Tarikh" 2/200 via Shu'bah as well, from Ja'far ibn Ma'bad, from Anas.