Offering three Rak`ahs for the `Asr Prayer forgetfully

Q: A day after performing `Asr (Afternoon) Prayer as three Rak`ahs (units of Prayer) only, a person remembers this, should he make up for it? (Part No. 5; Page No. 30

A: He should repeat the Salah as four Rak`ahs, for the Salah offered in this way is not valid.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.