It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) used to pray three rak'ahs of Witr and in them he would recite Surah Al-A'la, Surah Al-Kafiroon, and Surah Al-Ikhlas (in this order).
Hadith Referenceمسند احمد / ومن مسند بني هاشم / 2725
Hadith Gradingحکم دارالسلام:صحيح، شريك سيئ الحفظ، لكنه توبع