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 it does not contradict the first report, because it is to be understood as applying when the one praying is not following someone whom he is praying behind. For if the matter is as we have described, then if he were to return to rukuh, he would be adding an extra rukuh to his prayer, and that would invalidate the prayer. Moreover, such a return is only permissible for one who raised his head forgetfully; but if he did so deliberately, then it is not permissible for him to return to rukuh under any circumstance. And likewise, if he raises his head from sujud before the imam (of prayer), then let him return to his sujud so that his rising from it coincides with that of the imam (of prayer).