Sunan an-Nasa'i, Volume 1, Book 10, Hadith 823 (DarusSalam) ⓘ
It was narrated that Al Bara said: "When we prayed behind the Messenger of Allah I liked to be to his right."
أَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ، قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ، عَنْ مِسْعَرٍ، عَنْ ثَابِتِ بْنِ عُبَيْدٍ، عَنِ ابْنِ الْبَرَاءِ، عَنِ الْبَرَاءِ، قَالَ كُنَّا إِذَا صَلَّيْنَا خَلْفَ رَسُولِ اللَّهِ صلى الله عليه وسلم أَحْبَبْتُ أَنْ أَكُونَ عَنْ يَمِينِهِ .
also referenced under: Hadith 822 (Reference) & Book 10, Hadith 46 (In-Book)