The reading of the Quran and prostration

So what is the matter with them that they do not believe, and when the Quran is read
to them, they do not prostrate? But no! Those who disbelieved deny. God knows best
what they keep within themselves. So give them the news of a painful punishment.

84:20-24
Question:

Do the words in 84:21 mean that the believers have to prostrate on the ground whenever the Quran is being read?

Reply:

1- The words in these verses speak about the disbelievers. The words also imply that the believers prostrate when they hear the Quran being read, and poses the question as to why they do not prostrate like the believers do.

2- It is important to note that prostration on its own is not obligatory on the believers. The obligatory act is the Salat. The different acts observed during the Salat are all obligatory within the Salat, one of which is prostration.

3- The words 'la yasjudoon' in 84:21 mean 'they do not prostrate'. The noun of this verb is sujood which means prostration.
Traditional scholars added a sign at the end of 84:21 which makes it mandatory to prostrate at the end of this verse.
However, the instruction to prostrate at the end of 84:21 does not conform with the words in 84:21. The words do not speak about prostrating when 84:21 is read, it speaks about prostrating when the Quran is read. Naturally, the Quran includes all the verses and Suras in the Book and not just 84:21.

4- Some other scholars took a more lenient approach by changing the meaning of the words 'la yasjudoon' in 84:21 from 'they do not prostrate' to 'they do not submit'.

And so, they interpret 84:21 to mean:
'When the Quran is read to them they do not submit to it.'
However, changing the meaning of any Quranic word (in this case, changing the word sujood from prostrate to submit) in order to comply with a personal understanding, but without having concrete evidence, is a grave error. We should not accept such an interpretation.
And so, the word 'yasjudoon' in 84:21 means 'prostrate' just at it means prostrate throughout the Quran.

So with the correct meaning in mind, is God making it mandatory for the believers to prostrate on the ground every time the Quran is read? Remember that the words of the verse mentioned prostration when the Quran is read and not when 84:21 is read. The answer to this question is no.
For a start, in many homes the Quranic recitation is played for long hours. Are all who hear such extended recitation obliged to prostrate throughout those long hours. Certainly not. The Quran makes it clear that God does not wish for us any hardship in practicing our religion.

He has chosen you and has placed no hardship on you in the religion.
22:78

We also read:

God wants ease for you, and He does not want hardship for you.
2:185

So how should we understand 84:21 without changing the meaning of the word sujood to mean submission?
We have two important pieces of truth to consider for deriving the correct meaning:

1- The act of prostration is obligatory only within the Salat and not on its own. The Salat should not be observed without prostration, unless it is due to physical disability, or urgent circumstances, such as when space is not available as on a plane for example.

2- The words in 84:21 speak of prostrating when the Quran is read.

The only meaning that can be in harmony with both truths above is that all who hear the Quran, or in other words, receive the Quran are required to follow it and its law, one of which is observing the Salat. It follows that the act of prostration mentioned in 84:21 is symbolic of the Salat as a whole.

Even though this understanding is in harmony with the two truths above, we would still need Quranic evidence to confirm that it is the correct meaning. We need Quranic words that link the reading/recitation of the Quran and the observance of the Salat and that the believers are required to do both acts. This we find in the following verse:

Recite what is revealed to you of the Book and observe the Salat. 29:45

Those who believe, they recite the Quran and they observe the Salat. And naturally, when the Salat is observed, the act of prostration is also observed.

To conclude, in 84:21 God is asking why do the disbelievers not observe the Salat when the Quran is read to them and when they have received the Quranic message.