Missing the final sitting means the obligatory integral was not performed. Sitting for the required time but forgetting the tashahhud is a different issue: the sitting exists, while the wording is a distinct wajib.
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Case: No Final Sitting
Description of Prayer: The Six Obligations
Missing the final sitting means the obligatory integral was not performed. Sitting for the required time but forgetting the tashahhud is a different issue: the sitting exists, while the wording is a distinct wajib.