ENOfficial
Samura b. Jundub said: God’s Messenger commanded that when there were three of us one should stand in front. Tirmidhi transmitted it.
Source: sunnah.com
Other translations
Arabic
عَن سَمُرَة بن جُنْدُب قَالَ: أَمَرَنَا رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذَا كُنَّا ثَلَاثَةً أَنْ يَتَقَدَّمَنَا أَحَدُنَا. رَوَاهُ التِّرْمِذِيّ
sunnah.com