“Whoever rejects faith, his deeds have become worthless.”

And the Most High says, after mentioning the prophets:

“And from among their fathers, descendants, and brothers, We chose them and guided them to a straight path. That is Allah’s guidance, by which He guides whomever He wills of His servants. Had they associated partners with Him, all that they used to do would have become worthless.”

And He says:

“If you associate partners with Allah, your deeds will surely become worthless, and you will certainly be among the losers.”

This accords with His words:

“Indeed, Allah does not forgive associating partners with Him.”

If associating partners with Allah is not forgiven—and it entails remaining in the Fire forever—then it follows that the good deeds of the person who commits it are nullified. When He mentions sins other than disbelief, however, He does not make them grounds for nullifying all deeds.

As for His words:

“That is because they followed what angered Allah and disliked His pleasure, so He rendered their deeds worthless,”

this is because that constitutes disbelief. And His words:

“Do not raise your voices above the voice of the Prophet, nor speak loudly to him as you do to one another, lest your deeds become worthless while you do not realize it,”

are because such conduct may involve disbelief, thereby entailing the nullification of deeds without the person realizing it. The warning is to avert their nullification, or for fear of their nullification. He therefore forbade them from such conduct because it leads to disbelief, which entails the nullification of deeds.

There is no doubt that disobedience may lead to disbelief, as some of the early generations said: “Sins are the herald of disbelief.” They are therefore forbidden for fear that they may lead to the disbelief that nullifies deeds. As the Most High says:

“So let those who oppose his command beware lest a trial befall them”—meaning disbelief—“or a painful punishment afflict them.”

Iblīs disobeyed Allah’s command and became a disbeliever, while others were afflicted with a painful punishment.

The Khawārij and the Muʿtazilah have cited as evidence His words:

“Allah accepts only from the God-fearing.”