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Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
bayhaqi:2294 – Abū ʿAlī al-Rūdhbārī > Abū Bakr b. Dāsah > Abū Dāwud > Qutaybah > Ḥātim b. Ismāʿīl > Muṣʿab b. Thābit b. ʿAbdullāh b. al-Zubayr > Muḥammad b. Muslim b. al-Sāʾib Ṣāḥib al-Maqṣūrah > Ṣallayt > Janb Anas b. Mālik Yawm

one day I prayed by the side of Anas b. Malik. He said ; Do you know why this stick is placed here ? I said : No, by Allah. He said; The Messenger of Allah ﷺ used to put his hand upon it and say: Keep straight and straighten your rows. (Using translation from Abū Dāʾūd 669)   

البيهقي:٢٢٩٤ – أَخْبَرَنَا أَبُو عَلِيٍّ الرُّوذْبَارِيُّ أنبأ أَبُو بَكْرِ بْنُ دَاسَةَ ثنا أَبُو دَاوُدَ ثنا قُتَيْبَةُ ثنا حَاتِمُ بْنُ إِسْمَاعِيلَ عَنْ مُصْعَبِ بْنِ ثَابِتِ بْنِ عَبْدِ اللهِ بْنِ الزُّبَيْرِ عَنْ مُحَمَّدِ بْنِ مُسْلِمِ بْنِ السَّائِبِ صَاحِبِ الْمَقْصُورَةِ قَالَ صَلَّيْتُ إِلَى جَنْبِ أَنَسِ بْنِ مَالِكٍ يَوْمًا فَقَالَ

هَلْ تَدْرِي لِمَ صُنِعَ هَذَا الْعُودُ؟ قُلْتُ لَا وَاللهِ قَالَ كَانَ رَسُولُ اللهِ ﷺ يَضَعُ عَلَيْهِ يَدَهُ فَيَقُولُ اسْتَوُوا اعْدِلُوا صُفُوفَكُمْ  

See similar narrations below:

Collected by Abū Dāwūd
abudawud:669 – Qutaybah > Ḥātim b. Ismāʿīl > Muṣʿab b. Thābit b. ʿAbdullāh b. al-Zubayr > Muḥammad b. Muslim b. al-Sāʾib Ṣāḥib al-Maqṣūrah > Ṣallayt > Janb Anas b. Mālik Yawm

one day I prayed by the side of Anas b. Malik. He said ; Do you know why this stick is placed here ? I said : No, by Allah. He said; The Messenger of Allah ﷺ used to put his hand upon it and say: Keep straight and straighten your rows.  

أبو داود:٦٦٩ – حَدَّثَنَا قُتَيْبَةُ حَدَّثَنَا حَاتِمُ بْنُ إِسْمَاعِيلَ عَنْ مُصْعَبِ بْنِ ثَابِتِ بْنِ عَبْدِ اللَّهِ بْنِ الزُّبَيْرِ عَنْ مُحَمَّدِ بْنِ مُسْلِمِ بْنِ السَّائِبِ صَاحِبِ الْمَقْصُورَةِ قَالَ صَلَّيْتُ إِلَى جَنْبِ أَنَسِ بْنِ مَالِكٍ يَوْمًا فَقَالَ

هَلْ تَدْرِي لِمَ صُنِعَ هَذَا الْعُودُ فَقُلْتُ لاَ وَاللَّهِ قَالَ كَانَ رَسُولُ اللَّهِ ﷺ يَضَعُ يَدَهُ عَلَيْهِ فَيَقُولُ اسْتَوُوا وَعَدِّلُوا صُفُوفَكُمْ