which means worshipping Allah alone, without any partner. As Allah Most High says:

“We never sent any messenger before you without revealing to him: ‘There is no deity but Me, so worship Me.’”

He Most High also says:

“Ask those of Our messengers whom We sent before you: Did We appoint gods besides the Most Merciful to be worshipped?”

He Most High also says:

“We certainly sent a messenger to every nation, saying, ‘Worship Allah and shun false gods.’ Among them were those whom Allah guided, and among them were those upon whom misguidance was justly decreed.”

He Most High also says:

“O messengers, eat of good things and do righteous deeds. Indeed, I know all that you do.”

“Indeed, this religion of yours is one religion, and I am your Lord, so fear Me.”

All the messengers, including Noah, Hūd, Sālih, and others, said:

“Worship Allah, fear Him, and obey me.”

Thus, all the messengers called people to worship Allah alone, without any partner, and to obey them.

Belief in the messengers is “the second foundation” of Islam’s two foundations. Whoever does not believe that Muhammad is Allah’s Messenger to all the worlds, that all creation must follow him, that what is lawful is what Allah has permitted, that what is unlawful is what Allah has forbidden, and that religion is what He has prescribed, is an unbeliever. Such are these hypocrites and others like them who consider it permissible to depart from his religion, his law, and obedience to him—whether generally or in particular cases—and who consider it permissible to assist unbelievers and evildoers in corrupting his religion and his law.