One who makes zihar from his slave woman: does he free her?

Khalid bin Abi Imran said: I asked al-Qasim and Salim about a man who pronounced zihar against his slave woman and has no slave or the like to free; may he free that same slave woman? They said: "Yes."

Al-Dahhak said: If a person pronounces zihar against his slave woman, finds no slave or the like to free, is unable to fast, and intends to marry that slave woman, he should make her freedom her dower and free her as the expiation for zihar; she then becomes his wife.

It is narrated from Ibrahim that for a person who pronounces zihar against his slave woman, it suffices to free that same slave woman.

It is narrated from Tawus that if a person pronounces zihar against his umm walad and finds nothing with which to expiate, he should free her; freeing her will be the expiation for his oath.