What is the ruling on the prayer of one who prays behind an imam who is swift in movement and does not give him time to complete the pillar, so he begins bowing or rising before finishing the required remembrance?

Tranquility (ṭumaʾnīnah) is obligatory in all pillars of prayer. It is the stillness and settling of the limbs for the duration of one glorification (tasbīḥah). If you perform it while following your father in prayer, then your prayer is valid. However, if you rush so much that you do not achieve the sufficient measure of tranquility, then your prayer is invalid, and similarly, your father's prayer is invalid if he does not observe tranquility. The father should be advised not to rush in prayer, because the imam should be deliberate in his prayer out of consideration for the worshippers, so that they can complete their recitations and remembrances. It is not permissible for the imam to rush at a speed that prevents the worshippers from performing what is obligatory, and it is disliked for him to rush at a speed that prevents them from performing what is recommended.