“The parable of those who disbelieve in their Lord is that their works are as ashes, on which the wind blows furiously on a stormy day, they shall not be able to get aught of what they have earned. That is the straying, far away (from the Right Path).” (Qur’an, 14:18)
Allah has resembled the deeds of the disbelievers to ashes on which a severe wind blows during a stormy day, showing the futility and lack of benefit of those deeds.
So He compared their nullified actions with scattered dust because the actions were not based on the foundation of Imaan (faith) and Ihsaan. They were neither for Allah’s sake nor upon His command.
So such a person will not be able to benefit from his deeds at a time when he would need it the most (i.e. on the Day of Judgement). For this reason, Allah said, “they shall not be able to get aught of what they have earned.”
Hence, they will not be able to earn any reward or benefit from their deeds on the Day of Judgment. This is because Allah does not accept any deed unless it is done sincerely for His sake and in accordance with what He has legislated.
Actions are of four types. Only one type is accepted and the rest three are rejected. Only when the action is Al-Khaalis As-Sawaab (pure and correct), is it accepted. Al-Khaalis is sincerity for Allah’s sake alone and for none other than Him. As-Sawaab means the deed must be done according to how Allah legislated it upon the tongue of His Messenger (i.e. upon the Sunnah).
(The other three types are:
1. Deeds that are neither for Allah’s sake nor upon the Sunnah;
2. Deeds that are for Allah’s sake, but not upon the Sunnah;
3. Deeds that are upon the Sunnah but not done sincerely for Allah’s sake. These three types of deeds are rejected, while only the first type of deed – Al-Khaalis As-Sawaab – is accepted by Allah.)
There is a profound secret in (Allah’s) resembling of these (rejected types of deeds) with the ashes. Ashes come after the fueling and igniting of fire. Hence, such actions are the food of the fire (that will be destroyed). And it will also be the fuel of the Fire that will roast its inhabitants.
Allah will bring about (more) fire and punishment from their false actions, just as He brings about bliss and pleasure for the people whose deeds are purely for His sake alone and are in accordance with His command.
The Fire will affect the (rejected type of) actions until it turns them to ashes. Hence, such people, their actions, and what they worship besides Allah, are the fuel of the Fire.
– By Ibn Al-Qayyim Al-Jawziyyah
– Tafseer Al-Qayyim pg. 326-327