All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Cancer is a disease that is generally fatal. The fact that the patient has completed the treatment prescribed for him does not mean that he has been cured of the disease. {C}{C}
Therefore, if your father had gifted his property to some of his heirs when he had the disease that is feared to cause his death, then this gift takes the ruling of a will.
Ibn Qudaamah said in his book Al-Mughni:
“The ruling of gifting during an illness which one is feared to die, is the ruling of a will in five matters:
1- It is not effective if it exceeds one-third unless all the other heirs approve of it.
2- It is not valid for an heir, except with the permission of the rest of the heirs.
There is no doubt that his wife and his son are among the heirs. So, his gift to them during his disease in which he is feared to die is not effective and it is of no consideration because it is a will for an heir. Therefore, it is permissible for the remaining heirs to invalidate it and demand that those properties be divided Islamically amongst all of them.
If the wife insists on not invalidating this gift and prevents the heirs from taking their legitimate right from the properties, then there is nothing wrong in taking the matter to the court in order to repel her wrongdoing. This is not considered in itself an undutifulness to her, because one Companion took the case against his father to the Prophet and he did not consider it as a disobedience on the part of the son to his father.
Al-Bukhaari reported that Ma’n Ibn Yazeed, may Allah be pleased with him, said: “My grandfather, my father and I gave the pledge of allegiance to the Prophet . The Prophet got me engaged and then got me married, and one day I went to him with a complaint. My father, Yazeed, set aside some Deenaars (gold coins) for charity and gave them to a man in the mosque (so that he would give them to the poor) but I went to that man and took them and brought them to my father. Then my father said: ‘I swear by Allah! I did not intend to give them to you.’ Therefore, I took the case to the Prophet . Then, the Prophet said: ‘O Yazeed! You have been rewarded for what you intended, and as for you Ma’n! You are entitled to what you have taken.’” [Al-Bukhaari]
This Hadeeth is evidence that Ma’n Ibn Yazeed took a case against his father to the Prophet and that the Messenger of Allah ruled in his favor against his father as he approved that the money that he had taken was for him [i.e. he was entitled for it]. The Prophet did not reprimand him for taking a case against his father and he did not consider this to be an undutifulness on his part to his father.
Ibn Hajar said: “This is evidence that it is permissible for a father and his son to resort to arbitration, and that this, by itself, is not considered as undutifulness.” [End of quote]
For more benefit, please refer to Fatwa 124046.
Allah knows best.