The night prayer is prayed in units of two rakahs

A man asked the Messenger of Allah ﷺ about the night prayer, so the Messenger of Allah ﷺ said: "The night prayer is two ˹rakahs˺, then two ˹rakahs, and so on˺. Then, when one of you fears that dawn is near, let him pray one rakah, which will make odd what he has already prayed."

أَنَّ رَجُلاً سَأَلَ رَسُولَ اللَّهِ ﷺ عَنْ صَلاَةِ اللَّيْلِ، فَقَالَ رَسُولُ اللَّهِ ﷺ: «صَلاَةُ اللَّيْلِ مَثْنَى مَثْنَى، فَإِذَا خَشِيَ أَحَدُكُمُ الصُّبْحَ صَلَّى رَكْعَةً وَاحِدَةً تُوتِرُ لَهُ مَا قَدْ صَلَّى».

The Prophet ﷺ said, "Make witr as your last prayer at night."

عَنِ النَّبِيِّ ﷺ قَالَ اجْعَلُوا آخِرَ صَلاَتِكُمْ بِاللَّيْلِ وِتْرًا