If some waste matter is released from either passage should both be re-cleansed?

Q 1: If a person performs Istinja' (cleansing the private parts with water after urination or defecation) and cleanses both the front and back passage (urethra and anus), then some waste matter is released from either, will he be required to wash the front and back private parts again or only the one involved?

A: If some waste matter is released from the front passage it must be cleansed, and one need not wash the back passage also, because nothing was discharged from it.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.