The witr prayer is not obligatory like your prescribed prayers, but the Messenger of Allah ﷺ established it as a sunnah and said, "Indeed, Allah is One and loves what is odd-numbered, so perform the witr, people of the Quran."
حدثنا أبو كريب حدثنا أبو بكر بن عياش حدثنا أبو إسحق عن عاصم بن ضمرة
الوتر ليس بحتم كصلاتكم المكتوبة ولكن سن رسول الله ﷺ وقال إن الله وتر يحب الوتر فأوتروا يا أهل القرآن
Its chain of transmission is daif. It was also narrated by Ibn Majah, Establishing the Prayers, chapter on what has been said about Witr, no. 1169, and Nasai, 3/228, 229, no. 1676, from the hadith of Abu Bakr bin Ayyash, by the same route, and he was not the only one to narrate it. Abu Ishaq used ambiguous transmission wording (anana). Some corroborating reports are found with Ahmad, 1/107, and others.On this topic there are also reports from Ibn Umar [Ahmad, 2/2, no. 4834, 22/58, and Muwatta, 1/124], Ibn Masud [Abu Dawud, no. 1417], and Ibn Abbas [Ahmad, 1/331].