Sunan Abi Dawud 3926
سنن أبي داود#3926HasanNarrated 'Amr b. Shu'aib: on his father's authority, told that his grandfather reported the Prophet (ﷺ) said: A slave who has entered into an agreement to purchase his freedom is a slave as long as a dirham of the agreed price remains to be paid
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniHasan
Muhammad Muhyi Al-Din Abdul HamidHasan
Shuaib Al ArnautHasan
Zubair Ali ZaiIsnaad Hasan
In-book reference: 31:1