Was Muhammad a liar? Let’s check Koran and see what people said about Muhammad. But first:
Lying in Islam
Lying in Islam is permitted, unlike in Judaism and Christianity.
Liars

But first, Muhammad (“I”):
26:221 Shall I inform you upon whom the devils descend?
222 They descend upon every sinful liar.
223 They pass on what is heard, and most of them are liars.
Koran 26:221-223
Later the “Jinn” (AKA Muhammad) tell us in Koran:
72:8 And we have sought [to reach] the heaven but found it filled with powerful guards and burning flames. 9 And we used to sit therein in positions for hearing, but whoever listens now will find a burning flame lying in wait for him.
Koran 72:8-9
Someone, either Muhammad (“I”) or Muhammad (“Jinn”) is a liar here. As a reminder, what Muhammad thought were burning flames are:

Also sitting in space is pointless:

Muhammad as Shuaib

The “they” are Muhammad’s tribe, the Quraysh or Nabateans. Muhammad is the “you” and “He”. Muhamad is the liar as he’s proven wrong, “by Allah”, who didn’t punish his tribe. Instead, Muhammad invaded Mecca AKA Petra, murdered those who opposed him and forced everyone to be Muslims, thus showing Muhammad was a liar.
11:91 They said, “O Shuʿayb, we do not understand much of what you say, and indeed, we consider you among us as weak. And if not for your family, we would have stoned you [to death]; and you are not to us one respected.”
92 He said, “O my people, is my family more respected for power by you than Allāh? But you put Him behind your backs [in neglect]. Indeed, my Lord is encompassing of what you do. 93 And O my people, work according to your position; indeed, I am working. You are going to know to whom will come a punishment that will disgrace him and who is a liar. So watch; indeed, I am with you a watcher, [awaiting the outcome].”
Koran 11:91-93
Muhammad’s tribe threaten to stone him to death for being a lying false prophet.
26:185 They said, “You are only of those affected by magic. 186 You are but a man like ourselves, and indeed, we think you are among the liars. 187 So cause to fall upon us fragments of the sky, if you should be of the truthful.”
Koran 26:185-187
Muhamad is a liar as he’s unable to meet the challenge of his tribe.
[That occurred] when the messengers had come to them before them and after them, [saying], “Worship not except Allāh.”
They said, “If our Lord had willed, He would have sent down the angels, so indeed we, in that with which you have been sent, are disbelievers.”
Koran 41:14
Notice the incoherent lie of Muhammad talking about messengers AFTER the supposed end of Muhammad’s tribe. They picked up on this, showing they knew Muhammad was a liar with “so indeed we, in that with which you have been sent, are disbelievers.”
Muhammad as Saleh

“Thamud” refers to the people of Mecca, the Quraysh or Nabateans.
54:23 Thamūd denied the warning. 24 And said, “Is it one human being among us that we should follow? Indeed, we would then be in error and madness. 25 Has the message been sent down upon him from among us? Rather, he is an insolent liar.”
Koran 54:23-25
Muhammad was unable to correct them, to tell them to follow Allah, the god or idol, that they were already following and worshipping. Muhammad wanted power and wanted his tribe to follow him. The tribe was right, Muhammad was an “insolent liar.”
Muhammad the Meccan

The “they” are Muhammad’s tribe, the Quraysh or Nabateans in Petra, Jordan. The “eminent among them” are the rulers of the tribe.
38:4 And they wonder that there has come to them a warner [i.e., Prophet Muḥammad] from among themselves.
And the disbelievers say, “This is a magician and a liar. 5 Has he made the gods [only] one God? Indeed, this is a curious thing.”
6 And the eminent among them went forth, [saying], “Continue, and be patient over [the defense of] your gods. Indeed, this is a thing intended. 7 We have not heard of this in the latest religion. This is not but a fabrication. 8 Has the message been revealed to him out of [all of] us?”
Rather, they are in doubt about My message.
Rather, they have not yet tasted My punishment.
Koran 38:4-8
Notice that Muhammad’s tribe already worships Allah and the rest of the idols. The “eminent” complain that Muhammad’s “message” is not from Christianity (or Judaism). So the tribe already knew from their contacts with Jews and Christians, that their gods were idols, and that included Allah.
Then note that Muhammad speaks as Allah, but not to the tribe, but privately, to Muhammad. Obviously, this means that Muhammad is failing his supposed task as a prophet, messenger and warner. As he’s failing, this means he’s not a prophet, not a messenger, and not a warner. Thus, he’s a liar, making idols into what he wants, one idol, that he’s the priest of.
Muhammad the Demon Possessed

39:1 The revelation of the Book [i.e., the Qur’ān] is from Allāh, the Exalted in Might, the Wise.
2 Indeed, We have sent down to you the Book, [O Muḥammad], in truth.
So worship Allāh, [being] sincere to Him in religion.
3 Unquestionably, for Allāh is the pure religion.
And those who take protectors besides Him [say], “We only worship them that they may bring us nearer to Allāh in position.”
Indeed, Allāh will judge between them concerning that over which they differ.
Indeed, Allāh does not guide he who is a liar and [confirmed] disbeliever.
4 If Allāh had intended to take a son, He could have chosen from what He creates whatever He willed.
Exalted is He; He is Allāh, the One, the Prevailing.
Koran 39:1-4
Let’s compare these verses with what Muhammad said about his “revelation” from the hadith:
Narrated Aisha:
The commencement of the Divine Inspiration to Allah’s Messenger was in the form of good righteous (true) dreams in his sleep. He never had a dream but that it came true like bright day light. He used to go in seclusion (the cave of) Hira where he used to worship (Allah Alone) continuously for many (days) nights. He used to take with him the journey food for that (stay) and then come back to (his wife) Khadija to take his food like-wise again for another period to stay, till suddenly the Truth descended upon him while he was in the cave of Hira.
The angel came to him in it and asked him to read.
The Prophet replied, “I do not know how to read.”
(The Prophet added), “The angel caught me (forcefully) and pressed me so hard that I could not bear it anymore.
He then released me and again asked me to read, and I replied, “I do not know how to read,” whereupon he caught me again and pressed me a second time till I could not bear it anymore.
He then released me and asked me again to read, but again I replied, “I do not know how to read (or, what shall I read?).”
Thereupon he caught me for the third time and pressed me and then released me and said, “Read: In the Name of your Lord, Who has created (all that exists). Has created man from a clot. Read and Your Lord is Most Generous…up to….. ..that which he knew not.” (96:1-5)
Then Allah’s Messenger returned with the Inspiration, his neck muscles twitching with terror till he entered upon Khadija and said, “Cover me! Cover me!”
They covered him till his fear was over and then he said, “O Khadija, what is wrong with me?”
Then he told her everything that had happened and said, “I fear that something may happen to me.”
Khadija said, ‘Never! But have the glad tidings, for by Allah, Allah will never disgrace you as you keep good reactions with your Kith and kin, speak the truth, help the poor and the destitute, serve your guest generously and assist the deserving, calamity afflicted ones.”
Khadija then accompanied him to (her cousin) Waraqa bin Naufal bin Asad bin AbdulUzza bin Qusai. Waraqa was the son of her paternal uncle, i.e., her father’s brother, who during the Pre-Islamic Period became a Christian and used to write the Arabic writing and used to write of the Gospels in Arabic as much as Allah wished him to write. He was an old man and had lost his eyesight.
Khadija said to him, “O my cousin! Listen to the story of your nephew.”
Waraqa asked, “O my nephew! What have you seen?”
The Prophet described whatever he had seen.
Waraqa said, “This is the same Namus (i.e., Gabriel, the Angel who keeps the secrets) whom Allah had sent to Moses. I wish I were young and could live up to the time when your people would turn you out.”
Allah’s Messenger asked, “Will they turn me out?”
Waraqa replied in the affirmative and said: “Never did a man come with something similar to what you have brought but was treated with hostility. If I should remain alive till the day when you will be turned out then I would support you strongly.”
But after a few days Waraqa died and the Divine Inspiration was also paused for a while and the Prophet became so sad as we have heard that he intended several times to throw himself from the tops of high mountains and every time he went up the top of a mountain in order to throw himself down, Gabriel would appear before him and say, “O Muhammad! You are indeed Allah’s Messenger in truth” whereupon his heart would become quiet and he would calm down and would return home.
And whenever the period of the coming of the inspiration used to become long, he would do as before, but when he used to reach the top of a mountain, Gabriel would appear before him and say to him what he had said before.
Ibn `Abbas said regarding the meaning of: ‘He it is that Cleaves the daybreak (from the darkness)’ (6:96) that Al-Asbah. means the light of the sun during the day and the light of the moon at night).
Sahih al-Bukhari 6982
96:1 Recite in the name of your Lord who created 2 Created man from a clinging substance.
3 Recite, and your Lord is the most Generous – 4 Who taught by the pen 5 Taught man that which he knew not.
Koran 96:1-5
For Muhammad to “Recite” or “Read” he had to have a book AND the ability to “Recite” or “Read” it.
The Prophet replied, “I do not know how to read.”
Excerpt, Sahih al-Bukhari 6982
Thus you can see that the demon Jibril and Muhammad are liars.
45:6 These are the verses of Allāh which We recite to you in truth.
Then in what statement after Allāh and His verses will they believe?
7 Woe to every sinful liar 8 Who hears the verses of Allāh recited to him, then persists arrogantly as if he had not heard them.
So give him tidings of a painful punishment.
9 And when he knows anything of Our verses, he takes them in ridicule.
Those will have a humiliating punishment.
Koran 45:6-9
Notice that “We” didn’t know what verse from Allah will make them believe. Thus this shows that “We” is not omniscient and isn’t a real god. Thus, he’s a liar.
Notice “hear”. The demon didn’t know that Muslims would write down the verses spoken by Muhammad. This is yet another condemnation of the demon and Allah, for lacking omniscience. Thus this shows that Allah, Jibril the demon and Muhammad are liars.
Muhammad as Moses

40:23 And We did certainly send Moses with Our signs and a clear authority 24 To Pharaoh, Hāmān and Qārūn, but they said, “[He is] a magician and a liar.”
Koran 40:23-24
40:28 And a believing man from the family of Pharaoh who concealed his faith said, “Do you kill a man [merely] because he says, ‘My Lord is Allāh’ while he has brought you clear proofs from your Lord? And if he should be lying, then upon him is [the consequence of] his lie; but if he should be truthful, there will strike you some of what he promises you. Indeed, Allāh does not guide one who is a transgressor and a liar. 29 O my people, sovereignty is yours today, [your being] dominant in the land. But who would protect us from the punishment of Allāh if it came to us?”
Pharaoh said, “I do not show you except what I see, and I do not guide you except to the way of right conduct.”
Koran 40:28-29
40:36 And Pharaoh said, “O Hāmān, construct for me a tower that I might reach the ways 37 The ways into the heavens – so that I may look at the deity of Moses; but indeed, I think he is a liar.”
And thus was made attractive to Pharaoh the evil of his deed, and he was averted from the [right] way.
And the plan of Pharaoh was not except in ruin.
Koran 40:36-37
The “believing man from the family of Pharaoh” is Muhammad. He confirms that “Pharaoh” is the leader of Muhammad’s tribe and that both worship the same idol. Later, we know that Muhammad invaded, murdered those that opposed him and forced everyone to be Muslims. Thus, nothing of what Muhammad promised came true, showing Muhammad was a liar.
