What is the ruling on the prayer and sermon of one who has been performing ablution for ten years and is not certain about washing the entire hands, including the palms, during ablution?

Washing the hands in ablution includes the palms, even if they were washed at the beginning of ablution as a recommended act. Doubt about washing the palms after ablution does not affect its validity, and one should disregard obsessive thoughts. If you are certain that you did not wash them along with the hands in the obligatory washing, but you predominantly believe that the intention for obligation occurred when you washed them first, then the ablution is valid according to the Hanafis and Malikis due to the lack of obligation of order in ablution.