Assalamu alaykum. On a Q&A site, I saw a question that asked whether the devil (may Allah curse him) had more knowledge than the Prophet, sallallahu ʻalayhi wa sallam (I seek refuge in Allah from this), and the shaikh responded by saying that it is disrespectful and blasphemous to have such a belief. I suffer from Waswaas (devilish whisperings/obsessive doubts) about Kufr (disbelief). Therefore, this question got to me, and I want to make sure that I have a sound heart free of Kufr. I overanalyze things too much. My question to you is: could it be that the shaykh of this Q&A site was referring to knowledge about Allah (religious knowledge, and there is not doubt that the Prophet knows more about Allah than any other being)? So what about worldy knowledge, given taht the devil has been alive ever since the time of Adam, may Allah exalt his mention, and will remain so until the Day of Judgement? Please answer this question, because I do not want to have evil beliefs entering my heart lest I fall into Kufr. Please.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ʻalayhi wa sallam, is His slave and Messenger.

The type of knowledge that makes its acquirer worthy of praise and reward is the knowledge of Allah and the related knowledge of the divine Books, Messengers, the Last Day, and the details of the Shariah. There is no doubt that the Prophet, sallallahu ʻalayhi wa sallam, was at the pinnacle of such knowledge, and none of the jinn or human beings could ever come close to him in this regard, let alone excel over him. It was authentically reported that the Prophet, sallallahu ʻalayhi wa sallam, said, “I am the most knowling of Allah and the most fearful of Him among you.”

As for the knowledge of the details of worldly affairs which, if someone knows them, he is not praised, and if someone is ignorant of them, he is not dispraised, then someone other than the Prophet, sallallahu ʻalayhi wa sallam, might have more knowledge of it than him. This does not undermine the honorable status of the Prophet, sallallahu ʻalayhi wa sallam, in the slightest; Allah forbids. The Prophet, sallallaahu ʻalayhi wa sallam, said, “You are more knowing of the affairs of your world.” [Muslim]

It is most likely that this was what the shaykh meant.

In any case, you should disregard Waswaas and give it no attention whatsoever, as getting carried away with it leads to evil consequences.

Allah knows best.