Know, my brother and lord—may God support you—that for every doctrine there are opposites and devils who displace words from their places, making its people doubt and introducing likenesses upon it. This is inevitable. What supports what I have told you is the word of God—glory be to Him—as He says, and His word is the Truth:
{And when there came to them a messenger from God confirming that which was with them, a party of those who had been given the Scripture threw the Scripture of God behind their backs as if they did not know. And they followed what the devils recited over the kingdom of Solomon. It was not Solomon who disbelieved, but the devils disbelieved, teaching people sorcery and that which was revealed to the two angels at Babylon, Harut and Marut. But they do not teach anyone until they say, "We are only a trial, so do not disbelieve [by practicing magic]." And [yet] they learn from them that by which they cause separation between a man and his wife. But they do not harm anyone through it except by permission of God. And the people learn what harms them and does not benefit them. But the Children of Israel certainly knew that whoever purchased the magic would not have in the Hereafter any share. And wretched is that for which they sold themselves, if they only knew.}1
That is because it was related that after the occultation of Solomon ibn David—exalted be his glory—things were found in his books that contradicted one another; the devils had altered his books after his occultation, as God the Almighty informed with His saying: {It was not Solomon who disbelieved, but the devils disbelieved}2.
The knowledge of Truth does not contradict itself; rather, one part points to another and one part confirms another. The heretics were distinct from the prophets and the masters of the laws, saying: "There is nothing of the knowledge of Truth in their hands," and attributing it to sorcery and priesthood.