ENOfficial
Malik said he heard that a man asked Ibn ‘Umar whether the witr was obligatory, and ‘Abdallah said, “God’s Messenger observed the witr and the Muslims observed the witr.” The man kept repeating his question and ‘Abdallah kept saying, “God’s Messenger observed the witr and the Muslims observed the witr.” He transmitted it in al-Muwatta.
Source: sunnah.com
Other translations
Arabic
وَعَنْ مَالِكٍ بَلَغَهُ أَنَّ رَجُلًا سَأَلَ ابْنَ عُمَرَ عَنِ الْوِتْرِ: أَوَاجِبٌ هُوَ؟ فَقَالَ عَبْدُ اللَّهِ: قَدْ أَوْتَرَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَأَوْتَرَ الْمُسْلِمُونَ. فَجَعَلَ الرَّجُلُ يُرَدِّدُ عَلَيْهِ وَعَبْدُ اللَّهِ يَقُولُ: أَوْتَرَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَأَوْتَرَ الْمُسْلِمُونَ. رَوَاهُ فِي الْمُوَطَّأ
sunnah.com