What is the required conduct for the Imam regarding straightening the prayer rows?

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It is recommended for the Imam to straighten the prayer rows. This is done by turning to his right and saying, 'Straighten yourselves. May Allah have mercy upon you.' He then turns to his left and does the same. This is supported by the narration regarding the Prophet, peace be upon him, using a stick to ensure straightness, commanding people to stand straight and align their rows with the right hand, and then the left hand. Furthermore, straightening the rows is established as being part of the perfection of the prayer through the authenticated narration stating, 'Straighten your rows, for the straightening of the row is from the completeness of the prayer.'