What should one do who suffers from excessive self-talk before sleep, and says: "I have believed in Allah as Lord," then the whispers (waswas) return to him minutes later?

Thoughts and self-talk are forgiven by scholarly consensus, as long as they do not become settled and continuous within the person, because they are not within human control. The proof for this is the hadith: "Indeed, Allah has forgiven my Ummah for whatever thoughts cross their minds, as long as they do not act upon them or speak of them."

However, one must be careful not to dwell on these corrupt thoughts, because they can lead to evil actions. Thoughts are the devil's seeds in the heart, which he waters until they become firm intentions, and then they bear actions. It is recommended to occupy oneself with remembrances (dhikr), recitation (of Quran), and prayer.