Does changing one's sitting posture for the final Tashahhud while reciting it invalidate tranquility?

The worshiper's performing tawarruk (a specific sitting posture during prayer) during the tashahhud, or changing his sitting posture from one way to another, does not invalidate ṭuma’nīnah (tranquility) and does not nullify the prayer, as this falls under the category of minor actions.