knowledge of the Sunnah, then the one who emigrated earliest.” He thus distinguished knowledge of the Book from knowledge of the Sunnah, as the hadith indicates. Preference is given to one prospective imam over another only when they are equal in their knowledge of how to perform the prayer in the prescribed manner and in accordance with the Sunnah, and in the religious integrity required of an imam so that the follower’s prayer behind him is not deficient. If the two are equal in the completeness of both the prayers they perform themselves and those performed behind them, precedence is given to the more proficient reciter, followed by the one more knowledgeable of the Sunnah. Otherwise, the excellence of the prayer itself takes precedence over the qualities of its imam; and the knowledge and religious integrity required for it take precedence over what is merely recommended in these and other respects.

Some scholars, however, hold that congregational prayer is an emphatic Sunnah, while others hold that it is a communal obligation. They also differ regarding which prospective imam should be given precedence.

The imam instructs the congregation to form the rows properly, as the Prophet (peace and blessings be upon him) commanded, observing the five Sunnah practices concerning them: straightening the rows, closing the ranks, bringing the rows close together, filling the first row and then the next, and positioning the imam in the center. He must even forbid what the Prophet (peace and blessings be upon him) forbade—namely, a person praying alone behind the row—and instruct him to repeat the prayer, just as the Prophet (peace and blessings be upon him) instructed him to do in two soundly established hadiths in which he ordered the person praying alone behind the row to repeat his prayer; just as he ordered the man who prayed improperly to repeat his prayer; and just as he instructed the man who performed his ablution improperly