ENOfficial
Wabisa b. Ma'bad said that God’s Messenger saw a man praying alone behind the row and ordered him to repeat the prayer. Ahmad Tirmidhi and Abu Dawud transmitted it, and Tirmidhi said this is a hasan tradition.
Source: sunnah.com
Other translations
Arabic
وَعَنْ وَابِصَةَ بْنِ مَعْبَدٍ قَالَ: رَأَى رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ رَجُلًا يُصَلِّي خَلْفَ الصَّفِّ وَحْدَهُ فَأَمَرَهُ أَنْ يُعِيدَ الصَّلَاةَ. رَوَاهُ أَحْمَدُ وَالتِّرْمِذِيُّ وَأَبُو دَاوُدَ وَقَالَ التِّرْمِذِيُّ هَذَا حَدِيثٌ حَسَنٌ
sunnah.com