Hajjaj bin al-Minhal حجاج بن المنهال · The Book of al-Bay'ah

"I heard 'Ubadah bin As-Samit say: 'I pledged to the Messenger of Allah among a group of people, and he said: I accept your pledge that you will not associate anything with Allah, you will not steal, you will not have unlawful sexual relations, you will not kill you children, you will not utter slander, fabricating from between your hands and feet, and you will not disobey me when commanded with goodness. Whoever fulfills (this pledge), his reward will be…

"I stretched forth my hand to the Prophet for him to accept my pledge, when I was a child, but he did not accept my pledge."

"A slave came and pledged to the Prophet to emigrate, and the Prophet did not realize that he was a slave. Then his master came looking for him. The Prophet said: 'Sell him to me,' and he bought him for two black slaves. Then he did not accept the pledge from anyone until he asked: 'Is he a slave?"'