The Prophet (ﷺ) said, "Whoever manumits his share o a jointly possessed slave, it is imperative on him to manumit the slave completely if he has sufficient money to pay the rest of its price which is to be estimated justly. He should pay his partners their shares and release him (the freed one).
Sahih al-Bukhari Book 47, Hadith 19
← Previous Hadith that his mother Zainab bint Humaid took him to the Prophet (ﷺ) and said, "O Allah's Messenger (ﷺ)! Take the pledge of allegiance from him." But he said, "He is still too young for the pledge," and passed his hand on his (i.e. `Abdullah's) head and invoked for Allah's blessing for him. Zuhra bin Ma`bad stated that he used to go with his grandfather, `Abdullah bin Hisham, to the market to buy foodstuff. Ibn `Umar and Ibn Az-Zubair would meet him and say to him, "Be our partner, as the Prophet (ﷺ) invoked Allah to bless you." So, he would be their partner, and very often he would win a camel's load and send it home.

Sahih al-Bukhari Book 47, Hadith 18 Next Hadith → The Prophet (ﷺ) said, "Whoever manumits his share of a jointly possessed slave, it is essential for him to manumit the slave completely if he has sufficient money. Otherwise he should look for some work for the slave (to earn what would enable him to emancipate himself), without overburdening him with work."

Sahih al-Bukhari Book 47, Hadith 20