The obligation of “khums” is based on the command of Almighty Allah...
The obligation of “khums” is based on the command of Almighty Allah: “Know that whatever thing you may come by, a fifth of it is for Allah and the Apostle, for the relatives and the orphans, for the needy and the traveller (on the way person who does not have enough money), if you have faith in Allah and what We sent down to Our servant on the Day of Separation, the day when the two hosts met; and Allah has power over all things.” (8:41) Moreover, we believe that “Khums” is a right which Allah the Almighty particularly reserved for the descendants of The (PBUHH).
Since charity is unlawful for the children of the Holy Prophet (PBUHH) (they cannot receive zakat), “Khums” is a kind of compensation from the bounty of Allah, the Almighty. “Khums” is divided into six parts: three are for Allah, the Prophet and his Progeny (PBUTH); and the other three parts must be paid to the holy Imam when he is present to be spent for the orphans, the needy and the travellers (an on the way person who does not have enough money).
However, “Khums” should be handed over to the representative of the Imam, that is the just “Mujtahid” when the former is in occultation, The Imam is to use these funds to protect the religion of Islam and to complete the development plans of the Muslim nations. This is the real purpose for which is to be used. The remaining three parts of “Khums”, as we have said, are the right of the poor people.
Such were the commandments of “Khums” which have been followed from the time of the Holy Prophet (PBUHH) until now. After the death of the Holy Prophet (PBUHH), the Muslim rulers suppressed this right to “Khums” of the Al-Hashim (the progeny of the Prophet) and instead collected the money into the Muslim Treasury (Baytu ‘l-mal) in order that they themselves could control its use. This family, who had no right to “Zakat”, were now also deprived of “khums”.
It seems that Imam Shafi’i himself, in his book entitled “Al-Um”, pointed out that the descendants of the Prophet (PBUHH), for whom “Khums” was set aside in place of charity, can neither be given anything out of the prescribed charities, nor may they take it, and if the giver of charity knowingly gives it to them he will have to forego his heavenly reward.