Is the repentance prayer valid if it is performed long before bedtime with the same ablution used for the Witr prayer?

The repentance prayer (Salat al-Tawbah) is a supererogatory prayer performed for a specific reason. It is prescribed when a person commits a sin. The evidence for it is the Prophet's (peace and blessings be upon him) saying: "There is no servant who commits a sin, then purifies himself well, then stands and prays two rak'ahs, then seeks Allah's forgiveness, but Allah will forgive him."

As for Witr, it concludes the night prayer, so no prayer of repentance or any other prayer should be performed after it, due to the Prophet's (peace and blessings be upon him) saying: "Make the last of your prayers at night Witr."

Furthermore, habitually performing the repentance prayer every night before sleep has no evidence, and there is a concern that it might be an additional innovation (bid'ah idafiyyah).