We said to Anas bin Malik, "What do you find changed about our condition compared to the time of the Messenger of Allah ﷺ?"He replied, "I find that you do not straighten the rows in prayer."
حدثنا أبو معاوية حدثنا عقبة بن عبيد
قلنا لأنس بن مالك ما أنكرت من حالنا في عهد رسول الله ﷺ قال أنكرت أنكم لا تقيمون الصفوف
Its isnad is sahih. Abu Muawiya is Muhammad bin Khazim, and Uqba bin Ubayd, Abu Rihal, Tai, was accepted by the scholars. Bashir bin Yasar Harithi, their mawla, of Madinah, was trustworthy and a jurist.Bukhari narrated this hadith in Fath al-Bari, 2/209, no. 724, in the chapter on adhan, on the sin of one who does not complete the rows.