(Verily, those who do not believe in Allah's Ayat,) Allah will not guide them, and theirs will be a painful punishment, meaning, the disbelievers and heretics who are known to the people as liars. The Messenger Muhammad ﷺ, on the other hand, was the most honest and righteous of people, the most perfect in knowledge, deeds, faith and conviction. He was known among his people for his truthfulness and no one among them had any doubts about that - to such an extent that they always addressed him as Al-Amin (the Trustworthy) Muhammad. Thus when Heraclius, the king of the Romans, asked Abu Sufyan about the attributes of the Messenger of Allah ﷺ, one of the things he said to him was, "Did you ever accuse him of lying before he made his claim" Abu Sufyan said, "No". Heraclius said, "He would refrain from lying about people and then go and fabricate lies about Allah"
Ma'arif al-Qur'an
Mufti Muhammad ShafiOn ayahs 101–105
Sequence of Verses
In the previous verse (98), there was an instruction to say اَعُوذ بِاللہ 'a udhu bil-lah' (I seek protection with Allah) while reciting the Qur’ an which indicates that the Shaitan puts scruples in the heart when one recites the Qur'an. In the verses cited above, there is a refutation of such Satanic instigations.
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 102–104
The Quran is the Book of dawah. Its various parts were revealed bit by bit over a period of twenty three years. In consideration of the training of the believers, a gradual approach was adopted in respect of certain commandments. Taking advantage of such ‘changes’, the opponents of Islam used to say that the Quran was not the Book of God, but the Prophet Muhammad’s own writings which he attributed to God. They used to say that, if it had come directly from God, there would not have been such changes in it. Had these opponents been sincere and serious in the study of the Quran and had they looked upon the factor of change in the right perspective, they would have seen the wisdom of a gradual approach in giving orders. But when they saw the matter in the wrong perspective, changes appeared to them to be the result of a lack of human knowledge. A reasoned confirmation of these changes not being immediately forthcoming gave rise to the levelling of false allegations. The Quran has been revealed to present the Truth—here Truth means the pure and unadulterated religion of God. Those who are seekers after Truth and who are not satisfied with adulterated religions, will find not only the answer to their search in the Quranic religion but also peace of mind therein.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.