What is the ruling on yawning during prayer while reciting Al-Fatiha or the final Tashahhud, and what are the implications of continuing the recitation during the yawn without moving the tongue?

Previous fatwas have clarified that for Al-Fatiha and the obligatory ذكر (remembrances) in prayer, one must move the tongue such that the worshiper can hear himself. If one does not move his tongue for a single letter of Al-Fatiha, and thus does not recite it, his prayer is invalid. The same applies if he omits a single letter from the sufficient portion of the first Tashahhud (definition), and does not utter it, his prayer is invalid. What is said regarding the first Tashahhud also applies to the final Tashahhud, which is a pillar.