Will the pious person afflicted with doubt in faith be rewarded for his acts of worship, and what is the way to get rid of this condition?

If a Muslim is afflicted with whisperings (waswas) or doubts, let him say: "I believe in Allah," as the Prophet, peace and blessings be upon him, guided. Let him also contemplate Allah's creations and reflect upon them, for this increases faith. As for the whisperings of the self and intrusive thoughts that a person has no control over, he will not be held accountable for them. One should busy oneself with beneficial matters instead of dwelling on them, and he will be rewarded for that.