I suffer from ocd and i have resolved 70% of my phobias. I know for example that there is no sin if you imagine a blasphemous sentence or voice as long as you don't approve that. In one of the answers it said there is no sin but the believer must spent time with imagining good things like the Quran and sunnah. Because spending time with small and idle things is criticised because on the day of judgment Allah will ask us how we spent the time he gave us. But there remains a 30% that often keeps me awake at night. That 30% has to do with imagining visual things. Is it sinful to imagine a naked prophet or sahabah if you don't have the intention of belittling him or you don't have the intention of disrespecting Islam. Is it kufr? Is it major sin? Don't confuse with waswas. I mean you choose voluntarily to spend time thinking and imagining those things. But remember he doesn't have the intention of belittling him or he doesn't have the intention of disrespecting Islam. If you answer this question sincerely i will be celebrating the entire day because it will relieve me from an enormous amount of stress.
All perfect praise be to Allah, The Lord of the Worlds. I testify that none is worthy of worship except Allah and that Muhammad is His slave and messenger.
A person is not sinful for all these imaginations because Allah, out of His vast Mercy, has forgiven this nation for their thoughts as long as they do not act upon them or speak about them. Therefore, you are not sinful for what you have mentioned in the question.
However, you have to strive to guard your thoughts and preoccupy yourself by thinking about what will benefit you in your religion and your worldly matters in order to be cured from these whispers, Allah willing.
You have to strive against these whispers and try to get rid of them because giving in to them leads you to a great evil.
Allah Knows best.
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