Is a Muslim sinful if they doubt the correctness of their Quranic recitation during revision, and do not stop to verify, then the mistake or its absence becomes clear to them?

If a reciter doubts a word or a verse, he must investigate by asking or looking in the Mushaf (copy of the Quran) to preserve the Quran. It is permissible for him to act upon what he most likely believes to be correct, for the predominance of conjecture is equivalent to certainty in the rulings of Sharia. The jurists have not stated that it is obligatory to refer to the Mushaf or that there is sin for not doing so in this situation.