Once in Egypt, I had a debate with a man who is considered by the Jews to be the most renowned in knowledge and leadership. During the course of speech I said to him:
[Ibn Qayyim] «In disbelieving Muhammad (peace be upon him) you have discredited God in the most affronting way.»
[the Jewish scholar] «A man like you says that!?»
[Ibn Qayyim] «Listen to what I have to say. If you say that Muhammad is a tyrannical king who oppressed the people by the sword, who is not a messenger sent by God, who spent twenty three years assuming that he is the Messenger of God, sent out by God, to all the people of the world saying that God bid avail. And then, he says that God made it lawful for him to take into captivity the off-springs and the women of those disbelieve him and raise enmity against him, to pillage…their monies and possessions as booties of war, kill their men, and yet all but to no avail. And that he keenly endeavoured to change the religion of the prophets, evoke hostility and in their people, and abrogate their laws -; if this was the case, then it implies that either God, Most Sublime, was aware of it, seeing it happening and knowing it, or it escaped Him and He did not know about it. If you say He did not know about it, then you would have attributed to Him the most disgraceful degree of ignorance: for it means that a mortal who knew about it is more knowledgeable than He!. If you say that all of these happenings took place with His complete knowledge, it implies that either He was able and capable to have changed the course of events and prevented them, or He is not. If you say He is incapable, then you would have attributed to Him the most infamous degree of decreptitude which is contradictory to godhood. If he is capable but in spite of that He kept providing them with strength, victory, support, and elevation, advancing his word, answering his please, empowering him over his foes, showing through him what exceeds a thousand of miracles and virtuous wonders (Karamat), making him surmount he whoever reaches him with bad intentions, and answering every single plea he requested before Him; then your assumption is one of the gravest sorts of inequities and insolence that does not befit any of the prudent men: how about befitting the Lord of Heavens and the Earth Who bore witness to him by making him steadfast in his message, steadfast in what he says, and supporting him all the way through?!.» And you call this “false testimony” and “deception”!?
When he heard that he said:
[the Jewish scholar] *«God forbid! that He would help a lying impostor. On the contrary, he is indeed a truthful prophet. He who follows him will be prosperous and fortunate.»
[Ibn Qayyim] *«why do not you then embrace his religion?»
[the Jewish scholar] *«Because he was sent to the untaught people who had no Book. As for us, we do have a Book that we follow.»
[Ibn Qayyim] *«You have totally misconstrued the issue; he taught both the special people and the general public, and made it a widespread statement that he is the Messenger of God to All the people of the world, and that he who does not follow him is an unbeliever destined to be one of the folks of Hellfire. He fought against both. Since his message is proven to be true, believing in him in everything he told about is a must.»
[the Jewish scholar] He withheld from replying.
[source: Guidance to the Uncertain; In Reply to the Jews and the Nazarenes, 6/136-137] – Chosen by Shaykh Abu Abdur-Rahman