مسائل المنتخبه (Articles Of Islamic Acts) - الخوئي، السيد أبوالقاسم - الصفحة ٣١١ - Congregational Prayers

should recite qunut and tashahhud with the Imam, and the precaution is that, at the time of reciting tashahhud, he should place the fingers of his hands and the front part of his feet on the ground and raise his knees. And after the tashahhud he should stand up with the Imam and should recite Surah al Hamd and surah. And if he does not have time for the surah, he should complete Surah al-Hamd. and should join the Imam in bowing and if he cannot join the Imam in bowing he should, on the basis of obligatory precaution, make an intention of individual prayers.
١٤٤٩. If a person follows the imam, when he is in the second unit of the prayers consisting of four units, he should sit after the two prostrations in the second unit of his prayers, which is the third unit of the Imam, and should recite tashahhud to the extent it is obligatory, and should then stand up. And if he does not have time to recite the Tasbihat Arbaah thrice. he should recite the same once and should then join the Imam in bowing.
١٤٥٠. If the Imam is in the third or fourth unit and the follower knows that if he follows him and recites Surah al-Hamd he will not be able to join the Imam in bowing he should wait on the basis of obligatory precaution till the Imam goes in bowing and should then follow him.
١٤٥١. If a person follows the Imam, when he is in the state of qiyam of third or fourth unit he should recite Surah a[-Hamd and surah. and if he does not have time for the surah he should complete Surah al-Hamd and should join the Imam in bowing. And if he cannot join the Imam in bowing he should, on the basis of obligatory precaution, make intention for individual prayers.
١٤٥٢. If a person, who knows that, if he completes surah or qunut. he will not be able to join the Imam in his bowing, purposely recites surah or qunut and does not join the Imam in bowing what is more apparent is that his prayers is in order