حَدَّثَنَا سُفْيَانُ عَنِ ابْنِ أَبِي لَبِيدٍ عَنْ أَبِي سَلَمَةَ عَنِ ابْنِ عُمَرَ سَمِعْتُ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ سُئِلَ عَنْ صَلَاةِ اللَّيْلِ فَقَالَ مَثْنَى مَثْنَى فَإِذَا خِفْتَ الصُّبْحَ فَأَوْتِرْ بِوَاحِدَةٍ
مسند امام احمد بن حنبل · Hadith 4571
It was narrated from Ibn 'Umar: I heard the Prophet (PBUH) being asked about prayer at night. He said: "(The prayer at night) is two (rak'ahs) by two, then when you fear that dawn is about to break, make it odd numbered by praying one (rak'ah)."
Translated by Dr. Muhammad Muhsin Khan · Reviewed by Islamic University of Madinah · Published March 2020