The keeper of the maqsurah said, "One day I prayed beside Anas bin Malik, and he asked me, 'Do you know why this stick was made?'I replied, 'No, by Allah.'He said, 'The Messenger of Allah ﷺ used to place his hand upon it and say, Stand straight and align your rows.'"
حدثنا قتيبة حدثنا حاتم بن إسمعيل عن مصعب بن ثابت بن عبد الله بن الزبير
صاحب المقصورة قال صليت إلى جنب أنس بن مالك يوما فقال هل تدري لم صنع هذا العود فقلت لا والله قال كان رسول الله ﷺ يضع يده عليه فيقول استووا وعدلوا صفوفكم
Its isnad is daif. Ahmad narrated it (3/254) from the hadith of Hatim bin Ismail with this chain, and Ibn Hibban graded it sahih (8/389). Musab bin Thabit is daif, and Muhammad bin Muslim bin Saaib is majhul al-hal (of unknown status), as no one besides Ibn Hibban vouched for his reliability.