What is the ruling on the following action when in doubt about the number of prostrations after the final Tashahhud: interrupting the Tashahhud, then performing two prostrations, then repeating the entire Tashahhud, then performing the prostration of forgetfulness (sujood as-sahw) and the Tasleem? And does the prayer become invalid if this action was a mistake? And what is the correct action to take when in doubt about the number of prostrations?

If you doubt whether you performed one prostration or two, then you must perform one prostration, then the Tashahhud, then the prostrations of forgetfulness (sujud al-sahw), and then the taslim. However, your mentioned action of performing two prostrations instead of one is incorrect and invalidates the prayer, unless you were ignorant. But if you doubted the very act of prostration, then your action is correct. To search the website for the question number: Enter the Fatwa Center, then enter the number next to the word "Search," and choose "By question number" from the dropdown list.