Allah the Almighty sent Muhammad, peace be upon him, to be an illiterate Messenger. Allah the Almighty says, “You ˹O Prophet˺ could not read any writing ˹even˺ before this ˹revelation˺, nor could you write at all. Otherwise, the people of falsehood would have been suspicious.”[Al-Ankabut 29: 48]

The fact that he, peace be upon him, was illiterate is one of his miracles that indicates his truthfulness, and that whatever was revealed to him is from Allah the Almighty and not from himself, as the Almighty says, “He is the One Who raised for the illiterate ˹people˺ a messenger from among themselves - reciting to them His revelations, purifying them, and teaching them the Book and wisdom, for indeed they had previously been clearly astray - ”.[Al-Jumu’ah 62:2] Allah also says: “Indeed, Allah has done the believers a ˹great˺ favour by raising a messenger from among them - reciting to them His revelations, purifying them, and teaching them the Book and wisdom. For indeed they had previously been clearly astray.” [Aal-‘Imran 3: 164]. Had he, peace be upon him, not been illiterate, the Mushrikeen would have claimed that what he brought was from his own imagination and fabrication.

For the benefit of the reader, we would like to tell you this: The Mushrikun attributed what the Messenger of Allah, peace be upon him, brought to a non-Arab man, as the Almighty says, “And We surely know that they say, “No one is teaching him except a human.” But the man they refer to speaks a foreign tongue, whereas this ˹Quran˺ is ˹in˺ eloquent Arabic.”[An-Nahl 16:103]

This means: The Mushrikun said that the Qur’an was taught to the Prophet by someone who was non-Arab, and he used to sell his goods at As-Safa. The Messenger of Allah, peace be upon him, would sometimes sit with him and talk with him a little. However, that man was non-Arab, and he did not speak Arabic, and this is why Allah the Almighty said in response to their lies, “But the man they refer to speaks a foreign tongue, whereas this ˹Quran˺ is ˹in˺ eloquent Arabic.” [An-Nahl 16:103]. Since the Qur’an is revealed in an eloquent Arabic language, how could a foreign man teach the Prophet, peace be upon him all what is in the Quran, with all its eloquence and comprehensive meanings that are more perfect than the meanings of all other Divine Books that were revealed to the Children of Israel?

The scholars have different opinions about whether the Prophet, peace be upon him, learned to write after the mission or not. There are two opinions, and they supported their opinion that the Prophet, peace be upon him, was illiterate, with what Muslim reported from the Hadith of Al-Bara’ bin Azib in the Treaty of Al-Hudaybiyah: “It has been narrated on the authority of Bara’ who said: When the Prophet (PBUH) was checked from going to the Ka’bah, the people of Makkah made peace with him’ on the condition that he would (be allowed to) enter Mecca (next year) and stay there for three days, that he would not enter (the city) except with swords in their sheaths and arms encased in their covers, that he would not take away with him anyone from its dwellers, nor would he prevent anyone from those with him to stay on in Mecca (if he so desired). He said to ‘Ali: Write down the terms settled between us. (So ‘Ali wrote): In the name of Allah, most Gracious and most Merciful. This is what Muhammad, the Messenger of Allah, has settled (with the people of Makkah), The polytheists said to him: If we knew that thou art the Messenger of Allah, we would follow you. But write: Muhammad b. ‘Abdullah. So he told ‘Ali to strike out these words. ‘Ali said: No, by Allah, I will not strike them out. The Messenger of Allah (may Peace be upon him) said: Show me their place (on the parchment). So he (‘Ali) showed him their place and he (the Holy Prophet) struck them out; and he wrote: Ibn ‘Abdullah…)”

Had he known how to read and write, he would not have said that to Ali, may Allah be pleased with him, “Show me their place (on the parchment)”, As for the narrator's words, “and he wrote: Ibn ‘Abdullah…”, they indicate that the Prophet, peace be upon him, wrote, and this is the evidence of those who say that he learned to write. The more likely meaning is that he ordered the writing and did not write himself, for whoever orders a thing is counted as its doer. Basically, the Prophet, peace be upon him, was unlettered; had he moved from that to reading and writing, it would have been counted among his virtues, and the Companions would have transmitted and spread it. Nothing of the kind happened, which shows that he could neither read nor write. And Allah knows best.