Does the reprehensible category among the types of movement in prayer contradict the obligatory tranquility (ṭumaʾnīnah)? And if a worshipper keeps moving his hands throughout his bowing without stillness, is his bowing valid?

A disliked movement in prayer is a slight movement that is not necessary, such as slight fidgeting. It does not invalidate the prayer nor does it negate ṭuma’nīnah (tranquility). As for the movement that invalidates prayer, it is a movement considered excessive by custom, when it is not necessary. This is an independent invalidator, even if the worshipper achieves ṭuma’nīnah in the pillars. There is no necessary correlation between movement and the obligatory ṭuma’nīnah, which is attained by the slightest stillness or by the measure of the obligatory dhikr (remembrance), though there is a difference of opinion among scholars on this.