Is the prayer of one who doubted the opening takbir while praying with the congregation and then repeated it individually valid, and is the congregational prayer counted for him?

The majority of scholars dislike the congregant (ma'mum) raising his voice with the takbir, while the Malikis recommend it. It is sufficient for him to say it silently, meaning only hearing himself or moving his tongue. If the congregant pronounces the takbir, even by moving his tongue, his prayer is valid, and he earns the reward of congregational prayer. He is not legislated to repeat the prayer that he performed in this manner. He must beware of obsessive thoughts (waswas) and turn away from them.