What is the ruling regarding a husband not allowing his wife to rest when she is suffering from health problems and needs rest, and his refusal to acknowledge her illness?

Marriage is fundamentally based on affection (mawaddah) and mercy (rahmah). You should consider the verse: "And of His signs is that He created for you from yourselves mates that you may find tranquility in them; and He placed between you affection and mercy." (Quran 30:21), and reflect on how the Mothers of the Believers brought happiness to their husbands.

Winning hearts is achieved through cheerfulness and soft speech, as in His (Allah's) saying: "And not equal are the good deed and the bad deed. Repel [evil] with that which is best, and suddenly he to whom between you and him is enmity will become as though he was a devoted friend." (Quran 41:34).

If this applies to all people, then how much more so does it apply to a husband? A wife should relinquish some of her rights and forgive those who wrong her, for forgiveness increases a servant's honor.

As for the husband, he must fear Allah concerning his wife and treat her well, because Iblis places his throne upon water then dispatches his detachments, and the dearest of them to him is he who separates a man from his wife. Also, he (the husband) has been entrusted with his wife by the word of Allah.

The Prophet Muhammad (peace and blessings be upon him) was the best to his family, and he served his family, and he was considerate of his wives' feelings. He never said that illness has an age or a place, but rather he responded to the complaint of Aisha (may Allah be pleased with her). Thus, there is no excuse for a husband not to treat his wife kindly.