Is the prescribed sequence (Tarateeb) of reciting the Tashahhud before the Salat 'ala an-Nabi mandatory?
Chapter on the Description of Prayer
Al-Mughni
Book of Prayer
Primary text
It is a Sunnah to maintain the sequence and present the Tashahhud before the blessings upon the Prophet (PBUH). If one reverses the order without altering the meaning or omitting any obligatory part, there are two views. One view holds that it is valid because the intent (the meaning) has been achieved, making it valid like if the order was correct. This view is attributed to Al-Qadi and is the position of Al-Shafi'i.
Supporting text
The second view states that the prayer is invalid because the established sequence in the prescribed text has been violated, similar to how the order in the Adhan (call to prayer) is mandatory.