Is it permissible to give money to a poor father with the intention of charity?

The maintenance of a poor father who cannot find what suffices his basic needs is obligatory upon his children. This is a matter of consensus among scholars. Giving money to a poor father is a charity (sadaqah) in its broader sense. However, if his maintenance is not obligatory, then giving him money to expand his means is among the greatest acts of proximity [to Allah], especially if he is in need of it, and it is among the best charities. Nevertheless, it is not permissible to give zakat to the father if his maintenance is obligatory upon the zakat payer.