Is it permissible for a man to have sexual intercourse with his married slave woman?

It is not permissible for a man to have sexual intercourse with his married slave woman, and whoever does so has committed a forbidden act and deserves to be disciplined (ta'zir); because the married slave woman has become permissible for her husband, and a woman cannot be lawful for two men. Ibn Qudamah mentioned that whoever has intercourse with her incurs sin and deserves ta'zir, and that Imam Ahmad said he should be flogged and not stoned.