Ibn 'Umar (May Allah be pleased with them) reported:
The Messenger of Allah (ﷺ) used to perform his optional night prayers at night, two Rak'ah followed by two Rak'ah, and at the end he would conclude with an odd Rak'ah (Witr). Then he would perform two Rak'ah prayer before the dawn (Fajr) prayer after hearing the Adhan, and he would make them so brief as if he could hear the Iqamah being called.[Al- Bukhari and Muslim].
App reference: Book 9, Hadith 116
Arabic/English book reference: Book 9, Hadith 1106