Sunan Ibn Majah Book 5, Hadith 1236

حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا ابْنُ أَبِي عَدِيٍّ، عَنْ حُمَيْدٍ، عَنْ بَكْرِ بْنِ عَبْدِ اللَّهِ، عَنْ حَمْزَةَ بْنِ الْمُغِيرَةِ بْنِ شُعْبَةَ، عَنْ أَبِيهِ، قَالَ تَخَلَّفَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ فَانْتَهَيْنَا إِلَى الْقَوْمِ وَقَدْ صَلَّى بِهِمْ عَبْدُ الرَّحْمَنِ بْنُ عَوْفٍ رَكْعَةً فَلَمَّا أَحَسَّ بِالنَّبِيِّ ـ صلى الله عليه وسلم ـ ذَهَبَ يَتَأَخَّرُ فَأَوْمَأَ إِلَيْهِ النَّبِيُّ ـ صلى الله عليه وسلم ـ أَنْ يُتِمَّ الصَّلاَةَ قَالَ ‏ "‏ وَقَدْ أَحْسَنْتَ كَذَلِكَ فَافْعَلْ ‏"‏ ‏.‏

Hamzah bin Mughirah bin Shu’bah narrated that his father said:“The Messenger of Allah (ﷺ) lagged behind (on a journey) and we reached the people when ‘Abdur Rahman bin ‘Awf had already led them in one Rak’ah of the prayer. When he realized that the Prophet (ﷺ) was there, he wanted to step back, but the Prophet (ﷺ) gestured to him that he should complete the prayer. He said: ‘You have done well, do the same in the future.’”