Abdullah bin Abi Qais (may Allah have mercy on him) says that I asked Hazrat Aisha (may Allah be pleased with her) how many rak'ahs did the Prophet (peace and blessings be upon him) perform Witr upon? She replied: Four and three, six and three, ten and three, but he would not perform Witr on more than thirteen rak'ahs nor less than seven, and he would not leave the two rak'ahs before Fajr.