308 – Ṭalq ibn ʿAlī (may Allah be pleased with him) said: “I heard the Messenger of Allah ﷺ say, ‘There are not to be two Witrs in one night.’” Reported by Aḥmad and the three compilers of the Sunan, and declared authentic by Ibn Ḥibbān. ⦗1⦘

Hadith status
This report is ḥasan. It was transmitted by Aḥmad and the three Sunan compilers; Ibn Khuzaymah, Ibn Ḥibbān, ʿAbd al-Ḥaqq and others authenticated it, and al-Tirmidhī graded it ḥasan.

Points derived from the ḥadith
1 – The hadith shows that performing Witr twice or more in the same night is disliked, because repeating Witr in one night is an act of worship that has not been legislated; Allah is worshipped only in the manner He Himself has prescribed.

2 – If someone has already performed Witr and then wishes to pray again, that is permissible, as noted earlier. The Prophet ﷺ, after completing Witr, prayed two units, and the even-numbered prayer that follows Witr does not invalidate it.

3 – Whoever wants to remain with the imam until the imam finishes—so as to obtain the merit of the Prophet’s ﷺ saying, “Whoever stands with the imam until he departs, it is as though he has spent the whole night in prayer”—yet also wishes to make his own Witr the last prayer of the night, should, when the imam concludes with the salām, rise and add one rakʿah, thereby turning his congregational prayer into an even number.

It is stated in Sharḥ al-Zād with its marginal notes: If a person follows his imam in Witr, or performs Witr alone and then wishes to engage in night prayer, his original Witr is not nullified. He may pray as much as he likes until the second dawn appears, but he must not offer another Witr, for it is established that the Prophet ﷺ prayed two units after Witr and did not perform a second Witr. Should he choose to add a rakʿah and make the previous Witr even, that is permissible, and he will have gained both the virtue of following the imam and of having his Witr conclude his night prayers.