Read what he actually said to them

They came expecting to be told something terrible about themselves. They had reached the point of not being able to repeat the words, which anybody in this pattern will recognise.

He did not warn them. He did not ask what the thought was. He did not set them a course of correction.

He told them that the very distress they were in about it was the sign, and he called it clear faith. Which inverts the entire reading you have been running on your own experience. On his reading, the horror you feel at the thought is not evidence against your belief. It is evidence of it, because you have to hold something dear before its opposite can appal you.

And the report in Bukhari settles the legal side, which is that what passes through the mind, unacted on and unspoken, is overlooked.