Does the shaytaan know what crosses our minds of ideas which no one knows except Allah and thus whisper to us what is in accordance with our thoughts to instigate us in harboring negative thoughts and committing sins?.
Iblis whispers to mankind to lead them astray.
This whispering is speech that Iblis intends to be hidden from Allah, but of course, that is not possible.
Iblis uses ones' own thoughts against them, instilling doubts and fears.
However, the whispers of Iblis are just about meaningless.
So, looking closely at the ways that Iblis tries to lead mankind astray, we see rebelliousness, weakened faith, increased pride, conceit, laziness, Muslim-to-Muslim fighting, and disregarding obligatory deeds. Unfortunately, no human is immune from these thoughts at times, no matter how pious they are. Iblis has been watching humanity since its creation. He has had enough time to learn how humans think.
Iblis only knows what is in every human's mind, but he uses that to trick us into thinking that he sees into our hearts. Only Allah truly knows our thoughts.
Praise be to Allaah.
I had same issue after I read this I got cure alhamdulillah
Answers to this question cannot be verified. This question existed many centuries ago, many scholars had different (and contradicting) views.
I went by an arabic fatwa stating some of those views. You may use a translator if you wish.