Sunan an-Nasa'i, Volume 2, Book 20, Hadith 1715 (DarusSalam) ⓘ
Mansur reported from Al-Hakam, from Miqsam, that Umm Salamah said: "The Messenger of Allah used to pray witr with five and seven rak'ahs which he did not separate with any taslim nor talk."
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا جَرِيرٌ، عَنْ مَنْصُورٍ، عَنِ الْحَكَمِ، عَنْ مِقْسَمٍ، عَنْ أُمِّ سَلَمَةَ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُوتِرُ بِخَمْسٍ وَبِسَبْعٍ لاَ يَفْصِلُ بَيْنَهَا بِسَلاَمٍ وَلاَ بِكَلاَمٍ .
also referenced under: Hadith 1714 (Reference) & Book 20, Hadith 117 (In-Book)