Musannaf Ibn Abi Shayba 9:1521

Abu Dawud narrated to us, from Hammad ibn Salamah, from Qatadah, from al-Hasan, regarding a man who marries while he is ill. He said: If he was intending to cause harm, it is not permissible. And if he only married her so that she would care for him, then it is permissible.