It is your duty to cover the expenses of your father's treatment from your own money. Actually this is one of his rights asserted by the fact of being dutiful to and maintaining good ties with him. We hope that Allah will bountifully reward you for that. If your father willingly returns the money to you, which you spent on his treatment, or part of it, you will be allowed to take it. However, it is not permissible for you to demand all the money you assisted him with like debtors. It is not suitable to (Part No. 25; Page No. 262) do so with your father who brought you up, remained awake for your comfort and happiness and supported you financially until you grew up and became a man. To support this, it was related on the authority of
`Amr ibn Shu`ayb. From his father and grandfather that a man came to the Prophet (peace be upon him) and told him that his father took all his money. He (the Prophet) said,
"You and your property belong to your father."
Also, the Messenger of Allah (peace be upon him) said,
The most pleasant of what you eat is that out of what you earn; and your children are from your earnings.
Ibn Majah in his Sunan (Hadith compilations classified by jurisprudential themes)). Imam
Ahmad related a similar Hadith in his Musnad (Hadith compilation). In another narration, it was narrated that a man came to the Prophet (peace be upon him) to sue his father, saying, "O Messenger of Allah! My father needs my money [should I give it to him?]" Allah's Messenger (peace be upon him) said,
You and your property belong to your father.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.