The ruling on the prayer of one who omitted the first tashahhud believing it was not obligatory

Question : He says: Peace be upon you, and may Allah’s mercy and blessings be upon you. I say: And upon you be peace, and may Allah’s mercy and blessings be upon you. A woman, after learning and reading in books of Islamic jurisprudence, believed that in the final sitting of the prayer, she was only required to recite the salutation upon the Prophet (peace and blessings be upon him), so she limited herself to that for approximately three years. Then she was pointed out to the error, so she began to recite the tashahhud before the salutation upon the Prophet (peace and blessings be upon him and his family). What is the ruling on her prayers during that period?

Answer : The ruling is that she is not required to repeat them, because she was acting on a misunderstanding. For this reason, the Prophet (peace and blessings be upon him) did not order 'Ammar to repeat the prayer he performed with a tayammum that was not prescribed.