Is the father who raised the children more deserving than the real father who was absent for 40 years, and which of them is more entitled to receive financial support from the children?

The father's right to dutifulness, kindness, and financial support is fixed and does not lapse. His right is due to him being a father, not in exchange for his kindness, as Allah Almighty says: "And your Lord has decreed that you worship none but Him. And to parents, show kindness." Scholars have unanimously agreed on the obligation of a child to financially support needy parents. His right to financial support must be given precedence over others, even if others have provided for and raised him.

It is out of reciprocal kindness not to abandon the one who raised him, especially if he is in need, as Allah Almighty says: "Is the reward for good anything but good?" and the Prophet, peace and blessings be upon him, said: "Whoever does you a favor, then repay him."

The one who provided financial support can seek reimbursement from the father of the children under certain conditions, including that he did not intend it as a donation and that the father was wealthy at the time of the expenditure. Otherwise, he cannot demand reimbursement for what he spent. He can also seek reimbursement from the child he supported if the child had money from which it was difficult to spend on him, and the provider was aware of it, and the money remained until the time of his claim.