Should the Witr prayer be performed immediately after the Tarawih prayer, or should it be delayed to be the last prayer of the night?

If a Muslim prays Witr and then wishes to pray later in the night, he should pray two rak'ahs at a time, and not repeat the Witr prayer again, due to the Prophet's (peace and blessings be upon him) saying: "There are no two Witrs in one night." And it is authentically reported from Aisha (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) used to pray two rak'ahs after Witr while sitting. The Prophet's (peace and blessings be upon him) command that the last prayer of the night should be Witr is a matter of recommendation, not obligation.