The Prophet ﷺ spoke about a slave jointly owned by two men, one of whom frees his share. He said that the man is liable for compensation, and he said, "Whoever frees a portion of a slave, that slave is free at his expense."
و حدثناه عبيد الله بن معاذ حدثنا أبي حدثنا شعبة بهذا الإسناد قال من أعتق شقيصا من مملوك فهو حر من ماله