حَدَّثَنَا هَاشِمٌ حَدَّثَنَا اللَّيْثُ حَدَّثَنِي نَافِعٌ عَنْ عَبْدِ اللَّهِ عَنْ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَنَّهُ قَالَ صَلَاةُ اللَّيْلِ مَثْنَى مَثْنَى فَإِذَا خِفْتَ الصُّبْحَ فَأَوْتِرْ بِوَاحِدَةٍ وَاجْعَلْ آخِرَ صَلَاتِكَ وِتْرًا
مسند امام احمد بن حنبل · Hadith 6008
It was narrated from 'Abdullah from the Messenger of Allah (PBUH) that he said: "The night prayers are two (rak'ahs) by two, then if you are afraid that dawn is approaching, pray Witr with one (rak'ah), and make the last of your prayer Witr."
Sanad
حَدَّثَنَا هَاشِمٌ حَدَّثَنَا اللَّيْثُ حَدَّثَنِي نَافِعٌ عَنْ عَبْدِ اللَّهِ