The freed slave of the Messenger of Allah (ﷺ), Sayyiduna Thawban (may Allah be pleased with him), narrates that we were on a journey with the Messenger of Allah (ﷺ). He (ﷺ) said: "Indeed, this journey is a cause of hardship and fatigue, so when any one of you has prayed Witr, let him (also) pray two (additional) rak‘ahs. Then if he wakes up (for Tahajjud, it is better), otherwise those two rak‘ahs will suffice for him."
And that the two rak‘ahs which the Prophet, peace and blessings be upon him, used to pray after Witr were not specific to the Prophet, peace and blessings be upon him, alone to the exclusion of his ummah, since the Prophet, peace and blessings be upon him, has commanded us to perform the two rak‘ahs after Witr as a recommended and virtuous act, not as an obligatory or compulsory act.
Hadith Referenceصحيح ابن خزيمه / جماع أبواب ذكر الوتر وما فيه من السنن / 1106