Reciting (Surah) Al-Ikhlas in Witr is not Obligatory
Question :
Is the recitation of Surah As-Samad a condition for the acceptance of Witr or is it allowed for a person to recite any Surah in Witr?
Answer:
Reciting Surah Al-Ikhlas in Witr is not a condition for the acceptance of Witr; it is only a Sunnah according to the narration of Ahmad, Abu Dawud and An-Nasa'i, on the authority of Ubayy bin Ka'b and Ibn 'Abbas in which it is stated that the Messenger of Allah used to pray Witr with Surah Al-A'la, Surah Al-Kafirun and Surah Al-Ikhlas. But if any other Surahs are recited, the prayer will be correct, but he will lose the reward of following the Sunnah of the Prophet.
Source:
The Permanent Committee
Fatawa Islamiyah, Vol. 2 Page 307