Is it permissible to delegate someone to perform Hajj on behalf of one of the Companions who was unable to perform the obligatory Hajj? And is it possible to dedicate an endowment (waqf) to the Messenger of Allah, peace and blessings be upon him, and his Companions, and the Messengers?

It is not legislated to dedicate the reward of deeds to the Prophet (peace be upon him) or to his noble companions, and this is for several reasons: The righteous predecessors did not do it, and Allah praised those who came after them by saying that they seek forgiveness for those who preceded them in faith, which indicates that supplication (du'a) is superior. Furthermore, the Prophet (peace be upon him) receives a reward similar to that of his nation's deeds because he guided them to them, so dedicating the reward to him does not benefit him in any way and deprives the dedicator of its reward. Therefore, doing so is an innovation and not from the guidance of the noble companions.