Chapter on the Rulings of Congregational Prayer (the Minimum Number for Congregational Prayer, the Description of the Imam, Who Is to Be Followed and Who Is Not to Be Followed, Recitation Behind Both of Them, the Rulings of Those Led in Prayer, and Other Such Rulings Related to It)

So these two reports do not contradict what we previously mentioned, because of Imam عليه السلام statement, peace be upon him, in the first report, ‘If you reach the imam (of prayer) while he is bowing,’ and in the second, ‘and he has bowed,’ are to be understood as referring to catching up with him in the row (saff), which one is not allowed to delay joining in prayer if possible even if the takbir of rukuh was caught before reaching that place. For whoever hears the imam (of prayer) while he is pronouncing the takbir of rukuh, and there is a distance between them, it is permissible for him to say the takbir and bow with him at the place he reaches. Then, if he wishes, he may walk while in rukuh until he catches up with the imam (of prayer), or he may complete the prostration (sujud) in his place. When he finishes his two prostrations, he may then join the imam (of prayer) wherever he is. He may choose any of these options. And when we interpret these two reports in this manner, the narrations do not contradict one another. What indicates the permissibility of what we have mentioned is what was narrated: