When you have a bad suspicion about a Muslim in your heart
When you have a bad suspicion about a Muslim in your heart, you should increase your consideration toward him and make dua for him.
This way you will infuriate Satan and will be able to drive him away.
Because of this, Satan will be reluctant to put evil thoughts into your heart, afraid that you would increase your consideration towards your brother and will make dua for him again.
Abu Hamid al-Ghazali.