The whole notion of Islam, its origin is founded on the lie that Muhammad is "the Spirit of truth", of which Jesus spoke in John 16:5-15.
"“But now I go away to Him who sent Me, and none of you asks Me, ‘Where are You going?’ But because I have said these things to you, sorrow has filled your heart. Nevertheless I tell you the truth. It is to your advantage that I go away; for if I do not go away, the Helper will not come to you; but if I depart, I will send Him to you. And when He has come, He will convict the world of sin, and of righteousness, and of judgment: of sin, because they do not believe in Me; of righteousness, because I go to My Father and you see Me no more; of judgment, because the ruler of this world is judged.
“I still have many things to say to you, but you cannot bear them now. However, when He, the Spirit of truth, has come, He will guide you into all truth; for He will not speak on His own authority, but whatever He hears He will speak; and He will tell you things to come. He will glorify Me, for He will take of what is Mine and declare it to you. All things that the Father has are Mine. Therefore I said that He will take of Mine and declare it to you."
But Muhammad ignored John 15:26-27 and Acts Chapters 1-2. In Acts 1 Jesus promises the Spirit would come in weeks. Muhammad didn't show up for over 500 years.
"“But when the Helper comes, whom I shall send to you from the Father, the Spirit of truth who proceeds from the Father, He will testify of Me. And you also will bear witness, because you have been with Me from the beginning." John 15:26-27
"The former account I made, O Theophilus, of all that Jesus began both to do and teach, until the day in which He was taken up, after He through the Holy Spirit had given commandments to the apostles whom He had chosen, to whom He also presented Himself alive after His suffering by many infallible proofs, being seen by them during forty days and speaking of the things pertaining to the kingdom of God.
And being assembled together with them, He commanded them not to depart from Jerusalem, but to wait for the Promise of the Father, “which,” He said, “you have heard from Me; for John truly baptized with water, but you shall be baptized with the Holy Spirit not many days from now.” Therefore, when they had come together, they asked Him, saying, “Lord, will You at this time restore the kingdom to Israel?” And He said to them, “It is not for you to know times or seasons which the Father has put in His own authority. But you shall receive power when the Holy Spirit has come upon you; and you shall be witnesses to Me in Jerusalem, and in all Judea and Samaria, and to the end of the earth.”
Now when He had spoken these things, while they watched, He was taken up, and a cloud received Him out of their sight. And while they looked steadfastly toward heaven as He went up, behold, two men stood by them in white apparel, who also said, “Men of Galilee, why do you stand gazing up into heaven? This same Jesus, who was taken up from you into heaven, will so come in like manner as you saw Him go into heaven.”
Then they returned to Jerusalem from the mount called Olivet, which is near Jerusalem, a Sabbath day’s journey. And when they had entered, they went up into the upper room where they were staying: Peter, James, John, and Andrew; Philip and Thomas; Bartholomew and Matthew; James the son of Alphaeus and Simon the Zealot; and Judas the son of James. These all continued with one accord in prayer and supplication, with the women and Mary the mother of Jesus, and with His brothers.
And in those days Peter stood up in the midst of the disciples (altogether the number of names was about a hundred and twenty), and said, “Men and brethren, this Scripture had to be fulfilled, which the Holy Spirit spoke before by the mouth of David concerning Judas, who became a guide to those who arrested Jesus; for he was numbered with us and obtained a part in this ministry.”
(Now this man purchased a field with the wages of iniquity; and falling headlong, he burst open in the middle and all his entrails gushed out. And it became known to all those dwelling in Jerusalem; so that field is called in their own language, Akel Dama, that is, Field of Blood.)
“For it is written in the Book of Psalms:
‘Let his dwelling place be desolate,
And let no one live in it’;
and,
‘Let another take his office.’
“Therefore, of these men who have accompanied us all the time that the Lord Jesus went in and out among us, beginning from the baptism of John to that day when He was taken up from us, one of these must become a witness with us of His resurrection.”
And they proposed two: Joseph called Barsabas, who was surnamed Justus, and Matthias. And they prayed and said, “You, O Lord, who know the hearts of all, show which of these two You have chosen to take part in this ministry and apostleship from which Judas by transgression fell, that he might go to his own place.” And they cast their lots, and the lot fell on Matthias. And he was numbered with the eleven apostles.
When the Day of Pentecost had fully come, they were all with one accord in one place. And suddenly there came a sound from heaven, as of a rushing mighty wind, and it filled the whole house where they were sitting. Then there appeared to them divided tongues, as of fire, and one sat upon each of them. And they were all filled with the Holy Spirit and began to speak with other tongues, as the Spirit gave them utterance.
And there were dwelling in Jerusalem Jews, devout men, from every nation under heaven. And when this sound occurred, the multitude came together, and were confused, because everyone heard them speak in his own language. Then they were all amazed and marveled, saying to one another, “Look, are not all these who speak Galileans? And how is it that we hear, each in our own language in which we were born? Parthians and Medes and Elamites, those dwelling in Mesopotamia, Judea and Cappadocia, Pontus and Asia, Phrygia and Pamphylia, Egypt and the parts of Libya adjoining Cyrene, visitors from Rome, both Jews and proselytes, Cretans and Arabs—we hear them speaking in our own tongues the wonderful works of God.” So they were all amazed and perplexed, saying to one another, “Whatever could this mean?”
Others mocking said, “They are full of new wine.”
But Peter, standing up with the eleven, raised his voice and said to them, “Men of Judea and all who dwell in Jerusalem, let this be known to you, and heed my words. For these are not drunk, as you suppose, since it is only the third hour of the day. But this is what was spoken by the prophet Joel:
‘And it shall come to pass in the last days, says God,
That I will pour out of My Spirit on all flesh;
Your sons and your daughters shall prophesy,
Your young men shall see visions,
Your old men shall dream dreams.
And on My menservants and on My maidservants
I will pour out My Spirit in those days;
And they shall prophesy.
I will show wonders in heaven above
And signs in the earth beneath:
Blood and fire and vapor of smoke.
The sun shall be turned into darkness,
And the moon into blood,
Before the coming of the great and awesome day of the Lord.
And it shall come to pass
That whoever calls on the name of the Lord
Shall be saved.’
“Men of Israel, hear these words: Jesus of Nazareth, a Man attested by God to you by miracles, wonders, and signs which God did through Him in your midst, as you yourselves also know— Him, being delivered by the determined purpose and foreknowledge of God, you have taken by lawless hands, have crucified, and put to death; whom God raised up, having loosed the pains of death, because it was not possible that He should be held by it. For David says concerning Him:
‘I foresaw the Lord always before my face,
For He is at my right hand, that I may not be shaken.
Therefore my heart rejoiced, and my tongue was glad;
Moreover my flesh also will rest in hope.
For You will not leave my soul in Hades,
Nor will You allow Your Holy One to see corruption.
You have made known to me the ways of life;
You will make me full of joy in Your presence.’
“Men and brethren, let me speak freely to you of the patriarch David, that he is both dead and buried, and his tomb is with us to this day. Therefore, being a prophet, and knowing that God had sworn with an oath to him that of the fruit of his body, according to the flesh, He would raise up the Christ to sit on his throne, he, foreseeing this, spoke concerning the resurrection of the Christ, that His soul was not left in Hades, nor did His flesh see corruption. This Jesus God has raised up, of which we are all witnesses. Therefore being exalted to the right hand of God, and having received from the Father the promise of the Holy Spirit, He poured out this which you now see and hear.
“For David did not ascend into the heavens, but he says himself:
‘The Lord said to my Lord,
“Sit at My right hand,
Till I make Your enemies Your footstool.”’
“Therefore let all the house of Israel know assuredly that God has made this Jesus, whom you crucified, both Lord and Christ.”
Now when they heard this, they were cut to the heart, and said to Peter and the rest of the apostles, “Men and brethren, what shall we do?”
Then Peter said to them, “Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit. For the promise is to you and to your children, and to all who are afar off, as many as the Lord our God will call.”
And with many other words he testified and exhorted them, saying, “Be saved from this perverse generation.” Then those who gladly received his word were baptized; and that day about three thousand souls were added to them. And they continued steadfastly in the apostles’ doctrine and fellowship, in the breaking of bread, and in prayers. Then fear came upon every soul, and many wonders and signs were done through the apostles. Now all who believed were together, and had all things in common, and sold their possessions and goods, and divided them among all, as anyone had need.
So continuing daily with one accord in the temple, and breaking bread from house to house, they ate their food with gladness and simplicity of heart, praising God and having favor with all the people. And the Lord added to the church daily those who were being saved."
It was one of the greatest cons in history, driven by a lust for power. He was able to convince people that he, not the Holy Spirit of God, is the Spirit of truth.
https://www.biblegateway.com/passage/?search=Acts+1-2&version=NKJV