Fiqh-us-Sunnah Volume 2, Supererogatory Prayer, Fiqh 2.015.

Section : Recitation in the witr.

It is permissible to recite after al-Fatihah any surah which one wishes to recite. ‘Ali says: “There is not a part of the Qur’an that is obsolete, so make the witr prayer of whatever you wish from it.” However, it is preferred to recite, in the first of the three rak’at of witr, al-A’la after reciting al-Fatihah. In the second rak’ah, it is preferred to recite al-Kafirun. In the third rak’ah, it is proper to recite the last three surahs of the Qur’an. This is narrated by Ahmad, Abu Dawud and Tirmizhi, who relate from ‘Aishah, on sound authority saying: The Prophet sallallahu alehi wasallam would recite Ala’la in the first rak’ah, Al-Kafirun in the second and the last three surahs in the third rak’ah.