ENOfficial
It was narrated that a man from Banu Asad said: `Ali (رضي الله عنه) came out to us when the mu`adhdhin gave the call to Fajr prayer and said: The Messenger of Allah (ﷺ) has enjoined us to pray Witr and this is the time for it. Then he said: Give the iqamah for prayer, O Ibnun-Nawwahah.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، عَنْ أَبِي التَّيَّاحِ، حَدَّثَنِي رَجُلٌ، مِنْ عَنَزَةَ عَنْ رَجُلٍ، مِنْ بَنِي أَسَدٍ قَالَ خَرَجَ عَلِيٌّ حِينَ ثَوَّبَ الْمُثَوِّبُ لِصَلَاةِ الصُّبْحِ فَقَالَ إِنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَمَرَنَا بِوِتْرٍ فَثَبَتَ لَهُ هَذِهِ السَّاعَةَ ثُمَّ قَالَ أَقِمْ يَا ابْنَ النَّوَّاحَةِ.
sunnah.com