After the Messenger of Allah—may Allah bless him and grant him peace—passed away, Abu Bakr, may Allah be pleased with him, fought those people and declared: “By Allah, I shall fight anyone who separates prayer from zakah. By Allah, if they were to withhold even a rope—and in another wording, a young she-goat—which they used to hand over to the Messenger of Allah, may Allah bless him and grant him peace, I would fight them over it.”

Zakah is a due obligation upon wealth; it is one of the pillars of Islam. In the Quran it is paired with prayer in many verses, among them His saying:

“They were commanded only to worship Allah, devoting the religion exclusively to Him, as upright monotheists, to establish prayer and to give zakah.”

The evidence for tawḥīd appears at the very start of the verse in His words: “They were commanded only to worship Allah, devoting the religion exclusively to Him.” This is the explanation of tawḥīd: worshipping Allah alone with wholehearted sincerity and abandoning the worship of anything besides Him. Religion, tawḥīd, and worship all convey the same reality. “Devoting the religion exclusively to Him” means “devoting worship to Him alone.” This is the meaning of tawḥīd—not, as the scholastic theologians claim, merely acknowledging that Allah is the Creator, Provider, Giver of life and death. That is tawḥīd al-rubūbiyyah (the oneness of Lordship). What is required is tawḥīd al-ulūhiyyah (the oneness of worship), the message brought by the Messengers, and a person does not become a Muslim unless he realizes it.

Whoever confines himself to tawḥīd al-rubūbiyyah alone is not a Muslim, for the idol-worshippers believed in it, voiced it, and admitted it, yet it did not admit them