It was narrated from Umm Salamah that the Prophet (ﷺ) used to pray two short Rak’ah after Witr, sitting down.
Hadith Referenceسنن ابن ماجه / كتاب إقامة الصلاة والسنة / 1195
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:ضعيف, إسناده ضعيف, الحسن البصري عنعن, و ميمون بن موسي المرئي مدلس و عنعن (طبقات المدلسين 3/109), و حديث مسلم (738) و الترمذي (471) يغني عنه, انوار الصحيفه، صفحه نمبر 420
Hadith Takhrij« سنن الترمذی/الوتر 14 ( 471 ) ، ( تحفة الأشراف : 18255 ) ، وقد أخرجہ : مسند احمد ( 6/298 ) ( صحیح ) » ( اس کی سند میں میمون بن موسیٰ مدلس ہیں ، اور عنعنہ سے روایت کی ہے ، لیکن دوسرے شواہد سے یہ صحیح ہے ، ملاحظہ ہو : مصباح الزجاجة : 426 بتحقیق الشہری )
1؎: And some jurists were not aware of this report, so they prohibited the two units (rak‘ah) of supererogatory (nafl) prayer after witr. And perhaps the Messenger of Allah (sallallahu alayhi wa sallam) did this (i.e., refrained from praying after witr) occasionally, because he would mostly perform witr in the last part of the night, as has been mentioned above, and after witr he would not perform any other prayer until the break of dawn, at which point he would perform the sunnah prayers of Fajr.
´Umm Salamah narrated:` "The Prophet would pray two Rak'ah after Al-Witr."
Shaykh Dr. Abdur Rahman Freywai
1: According to Nawawi, the Prophet sallallahu alayhi wa sallam’s performing two units of prayer after Witr was to demonstrate permissibility. He did not always do so, nor could he have done so consistently, as he himself said: “Make Witr the last of your night prayers (tahajjud),” so how could he himself act contrary to this? Or, it may be understood that this was something specific to him, and perhaps this is the reason that the scholars of the Ummah did not adopt this practice. And Allah knows best.
Source: Sunan al-Tirmidhi – Majlis ‘Ilmi Dar al-Da‘wah, New Delhi Edition, Page: 471