وَإِنَّهُ لَحَقُّ اليَقينِ
It is indeed certain truth.
EXEGESIS
It is indeed certain truth is once again referring to the Quran as being beyond any doubt. This is a conviction that is held by the faithful and, in particular, by the foremost ones (al-sābiqūn) (56:10) amongst them, as noted in the Introduction. For the faithful, ultimate truth is what God declares to be so, because only He is omniscient, possessing perfect knowledge of all matters.
The prefix particles and pronouns, wa (and), inna (indeed), huwa (it), put together, are all for emphasis, to re-affirm that this, the Quran and what it states, truly deserves to be called the certitude (yaqīn) of truth (ḥaqq). Other matters fall short of that level of certitude, and if they oppose the Quran they are mere conjectures, no matter how certain they may seem to you.
Ḥaqq (truth) of course is absolute and never changes whereas yaqīn (certainty) relates to man’s conviction in the truth about something. So, whereas the former is ontological, the latter is epistemological. Used together, as certain truth (ḥaqq al-yaqīn), the certainty becomes an adjective describing and corresponding to the truth. The verse uses the two terms together as an emphasis, to say this Quran is the truth ontologically and epistemologically, or, in simpler terms, an absolutely certain truth and beyond any doubt, both as an independent reality outside man’s knowledge and to the degree that man can comprehend the absolute truth and be certain of it.
EXPOSITION
Muslim theologians also explain ḥaqq al-yaqīn as the highest form of conviction and truth by contrasting it with two other forms of conviction using the following analogy: when one sees smoke, one may surmise there is fire without seeing it. This form of conviction is called ʿilm al-yaqīn (certain knowledge) because the certainty is not derived from seeing but from knowledge and experience. Thereafter one might get closer and see the fire. This would be a witnessing that results in ʿayn al-yaqīn (witnessed certainty). But eyes too can deceive. By far the greatest conviction would be for one to get even closer and feel the fire’s heat and touch it. This is ḥaqq al-yaqīn (certain truth). Beyond this, there cannot be any doubt. The interpretation of this verse is therefore as follows: the Quran is pure certainty and if one were to imagine levels of certainty, there would be none above this. The first two forms of convictions are described in the verses: No indeed! Were you to know with certain knowledge (ʿilm al-yaqīn), you would surely see hell. Then you would surely see it with the eye of certainty (ʿayn al-yaqīn) (102:5-7).