فَوَيْلٌ لِّلْمُصَلِّينَ
The first three verses described the one who denies the religion. The reader was safe while listening to it: the one described is somebody else, he is outside, he is not me. In the fourth verse the target changes and those who pray is said.
The violence of this change must not be missed. Had the sūra said "woe to the disbelievers" nothing would have happened. Nor would anything have happened had it said "to the hypocrites" — the hypocrite is a bad man already, no one looks for himself there. But when muṣallīn — those who pray — is said, the sentence comes straight down upon the listener. Because the listener does pray.
The technique here is this: the sūra first sets up a "them", puts the reader at ease, and then draws the line over to the reader's own side. This is not a text that points outward; it is a mirror.
The letter fāʾ joins the two halves to one another. That is, the "woe" sentence is not an independent addition but the continuation and the consequence of what precedes. The conjunction signals from the very outset that the two groups in fact meet on the same matter.
The meaning of the word. Wayl is a word in Arabic conveying destruction, torment, severe evil and ruin. It is rendered into English as "woe", but that rendering stays weak; "woe" conveys pity, whereas wayl conveys imprecation and sentence. A closer equivalent: "damnation on him", "let him perish".
The word's opposite occurs in the Qurʾān: ṭūbā (blessedness be his). Wayl is the exact contrary of ṭūbā.
In the reports it is said that wayl is the name of a valley or of a pit in Hell. This is not a piece of information coming from the dictionary sense of the word but an explanation resting on exegetical reports, and their chains are disputed. The word's real function in the language is not to be a place-name but to be a declaration of ruin.
A grammatical point. Waylun is an indefinite (nakira) word and it is the subject at the head of the sentence. Arabic grammar does not normally look kindly on beginning a sentence with an indefinite word; the reason this is allowed here is that the sentence carries the sense of a prayer or imprecation.
But the indefiniteness itself carries meaning too. The indefiniteness here is for magnification and for striking dread (tafkhīm, tahwīl): "such a wayl as has no description". Had it been definite, a known torment would have been spoken of; left indefinite, its limit is not drawn but left open.
The other instances of wayl in the Qurʾān. It is instructive to look at whom this word is directed. Al-Muṭaffifīn 83/1: "Woe to those who give short measure and short weight!" — that is, to people who in trade give little and take much. If you see wayl at the head of a verse, what you have before you is most often either denial or the shortchanging of another's right. The wayl in al-Māʿūn falls exactly into this second category.
The word. Muṣallī means "one who performs the prayer"; an active participle from the tafʿīl form. Root ص ل و.
There are several views on the original sense of the root. The widespread one is supplication — ṣalāt in Arabic is supplication. Another explanation attaches it to the word ṣalawān: the two bones at the lower end of the back, in the region of the tailbone. On this view the word comes from the movement of bending in the bowing.
A usage transmitted by the lexicographers stands here particularly well: in horse races the horse that comes in second is called muṣallī — because its head comes close to the ṣalawān of the horse in front of it. That is, muṣallī, in the word's most concrete state, means "the one who comes right behind, who follows, who goes on the heels of another".
This image tells what the prayer is better than a definition does: the one who prays is a person who has accepted going after someone who goes in front. I pass this on as a point about language; it carries no value as a ruling, but it shows the picture behind the word.
The definite article and the critical point. The verse does not say "li-muṣallīn" (to some who pray), it says "li'l-muṣallīn" (to those who pray). Definite. But which ones?
The answer is in the next verse. And because this is the most misunderstood place in the sūra, it must be said plainly:
The verse does not end here. The fourth verse is not a completed sentence without the adjectival clause in the fifth.
Grammatically alladhīna hum ʿan ṣalātihim sāhūn is an adjectival (naʿt) clause; it qualifies muṣallīn, it does not set up a group separate from them. If the qualifier is removed the sentence says something entirely different — and wrong: woe to the prayer itself.
For this reason to quote this verse on its own is to corrupt the text. The sūra passes judgement not on the prayer but on a particular state of prayer.
And there is this too: why does the verse, instead of saying "the disbelievers", say by a roundabout route "those who pray"? Because what is targeted is contenting oneself with the prayer itself. A person counts his praying as an identity document, a document of acquittal. The sūra invalidates this document: the presence of the service does not excuse that service's producing no result.