Sunan Abi Dawud 663
سنن أبي داود#663SahihAl-Nu’man b. Bashir said:the prophet (ﷺ) used to straighten us in the rows of prayer as the arrow is straightened, until he thought that we had learned it from him and understood it. One day he turned towards us, and shoulders in order, and say; Do not be irregular. And he would say: Allah and his Angels bless those who near the first rows
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Zubair Ali ZaiSahih Muslim (436)
In-book reference: 2:273