Sayyiduna Anas (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) used to perform nine rak‘ahs of Witr. Then, when the Prophet (peace and blessings be upon him) became older, he started performing seven rak‘ahs of Witr, and he (peace and blessings be upon him) would perform two rak‘ahs sitting, in which he would recite Surah ar-Rahman and Surah al-Waqi‘ah. Sayyiduna Anas (may Allah be pleased with him) narrates that we would recite short surahs, such as «‏‏‏‏قُلْ يَا أَيُّهَا الْكَافِرُونَ» ‏‏‏‏ and similar surahs.