Fiqh-us-Sunnah Volume 3, Zakaat and Fasting, Fiqh 2.151B.

In reference to the life hereafter, Allah reveals: “Lo! Those who keep from evil will dwell amid gardens and water-springs, taking that which their Lord gives them. For they were before doers of good. They used to sleep but little of the night, and in the hours of the early dawn they prayed for forgiveness… In their wealth, the beggar and the outcast had due share” [azh-Zhariyat 15-19]. Allah views beneficence and righteousness as exclusive qualities of the pious. It is because of their beneficence that they pray at night and ask Allah’s forgiveness at dawn as a way of worshipping and approaching Him. Their beneficence is likewise in their giving to the needy their share of mercy and sympathy.

Allah further confirms: “And the believers, men and women, are protecting friends of one another; they enjoin the right and forbid the wrong, they perform prayer and pay the zakah, and they obey Allah and His Messenger. Upon them, Allah will have mercy” [at-Taubah 71].

Such are the people blessed by Allah and given His mercy – those who believe in Him, who take care of each other through support and love, who exhort fairness and restrain lewd behaviour, who have strong ties with Allah through prayer, and who strengthen their mutual relations through zakah.

Finally, these people, as reflected in al-Hajj 41, are: “Those who, if we give them power in the land, perform prayers and pay zakah, and enjoin kindness and forbid inequity.” Giving zakah is, therefore, one of the reasons for which the righteous are given authority on earth.