Is it permissible to give zakat to my cousin (my father's sister's son) whose financial situation has temporarily deteriorated due to the costs of his son's cancer treatment?

It is permissible to give the poor father from zakat to treat his son who is unable to earn a living, because the cost of treating the son is obligatory upon the father. In this case, the father is considered eligible for zakat due to his inability to cover his obligatory expenses; rather, he is more deserving of it due to his kinship and need. However, if the father is able to bear the costs of his son's treatment and has enough for his basic needs, then it is not permissible to give him zakat.