Witr is not incumbent like the status of the obligatory prayers, but it is a Sunnah that the Messenger of Allah (may Allah's peace and blessings be upon him) started practicing
Chapter: What Has Been Related About Al-Witr Is Not Incumbent
Weak
graded by Zubair Ali Zai
Jami' at-Tirmidhi 454
الْوِتْرُ لَيْسَ بِحَتْمٍ كَهَيْئَةِ الصَّلاَةِ الْمَكْتُوبَةِ وَلَكِنْ سُنَّةٌ سَنَّهَا رَسُولُ اللَّهِ صلى الله عليه وسلم
‘Ali (may Allah be pleased with him) said: "Witr is not incumbent like the status of the obligatory prayers, but it is a Sunnah that the Messenger of Allah (may Allah's peace and blessings be upon him) started practicing."
Reported by At-Tirmidhi (No. 454), An-Nasa’i (No. 1676) and Ahmad (No. 617, 722, 747, 883, 1157, 1169).
The Hadīth means that performing the Witr prayer is not obligatory like the obligatory five daily prayers, but it is a Sunnah that the Messenger of Allah (may Allah's peace and blessings be upon him) established. This last part of the Hadīth stresses the fact that the Witr prayer is desirable and recommended only, and the Messenger of Allah (may Allah's peace and blessings be upon him) performed it without making it obligatory upon us.
Explanation in Arabic
معنى الحديث: صلاة الوتر ليس بواجبة، كالصلوات الخَمس، ولكن سُنَّة سَنَّها رسول الله صلى الله عليه وسلم ، أي: أن النبي صلى الله عليه وسلم سَنَّ لنا الوِتر ولم يُوجبه علينا، وهذا تأكيد لقوله: "ليس بِحَتم"، فالوتر صلاة مستحبة ومندوبة فقط.