Question: There is no doubt that the Holy Prophet (S) has not demanded anything in return of the efforts and hardships he had borne to guide the humanity. He has sought the recompense of this only from the Almighty Allah.
But we see that in some Qur’anic verse, like the verse of Mawaddat the love of Ahlul Bayt (a.s.) is termed as the recompense of Prophethood due to the fact that this love is a favor upon the people themselves and a channel for their guidance because wilayat (Guardianship) of Ahlul Bayt (a.s.) becomes a cause to follow the words and actions of these noble personages.
This itself is a kind of guidance and righteousness, which is bestowed on the people through a medium. But what is the reason for making Khums obligatory (half of which is the share of Sadaat)? Is it not a price for Prophethood?
Answer: As well all know Khums is not for every Sadaat. It is only for those who are needy. If the amount of Khums exceeds the needs of Sadaat it has to be deposited in the Islamic treasury (according to the commands that have reached us) so that it can be spent for common food of the people. In the same way if the needs of the poor Sadaat is more than the Khums paid by the people the deficit has to be made up by the Baitul Maal (Islamic treasury). On the other hand the Sadaat are prohibited to receive Zakat which is the right of other needy people (Even if the Zakat is taken from rich Sadaat).
Therefore actually Khums is in place of Zakat which is paid to other needy people and the requirements are same as for the recipients of Zakat. But in order to maintain the honor of the Holy Prophet (S) and as a mark of respect its payment has been given another form and another title (Khums instead of Zakat). It is a mark of respect for the esteemed position of the Holy Prophet (S) and it is not in any way a sort of recompense or price. Obviously, there is a wide difference between maintaining respect of honor of exalted personalities and paying a price.