(Imām Bukhārī narrates): Mu'ādh ibn Asad narrated to us, he said: Al-Fadl ibn Mūsā informed us, he said: Sa'īd ibn 'Ubaid al-Tā'ī informed us, from Bashīr ibn Yasār al-Ansārī, from Anas ibn Mālik al-Ansārī, may Allāh be pleased with him, he narrates that:
he came to Madīnah. He was asked: Since the time of the Messenger of Allāh ﷺ has passed, what thing do you find changed (contrary to what it used to be)? He said: I find nothing changed except that you do not keep the rows straight.
And 'Uqbah ibn 'Ubaid said, from Bashīr ibn Yasār: Anas ibn Mālik came to us with this same saying.
حَدَّثَنَا مُعَاذُ بْنُ أَسَدٍ، قَالَ أَخْبَرَنَا الْفَضْلُ بْنُ مُوسَى، قَالَ أَخْبَرَنَا سَعِيدُ بْنُ عُبَيْدٍ الطَّائِيُّ، عَنْ بُشَيْرِ بْنِ يَسَارٍ الأَنْصَارِيِّ، عَنْ أَنَسِ بْنِ مَالِكٍ، أَنَّهُ قَدِمَ الْمَدِينَةَ فَقِيلَ لَهُ مَا أَنْكَرْتَ مِنَّا مُنْذُ يَوْمِ عَهِدْتَ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ مَا أَنْكَرْتُ شَيْئًا إِلاَّ أَنَّكُمْ لاَ تُقِيمُونَ الصُّفُوفَ. وَقَالَ عُقْبَةُ بْنُ عُبَيْدٍ عَنْ بُشَيْرِ بْنِ يَسَارٍ قَدِمَ عَلَيْنَا أَنَسُ بْنُ مَالِكٍ الْمَدِينَةَ بِهَذَا.
Reference: Sahih Al Bukhari 724