Question :

Is it permissible to make ablution without answering the call of nature after waking up?

The Answer :

Washing front and back openings(Istinjaa`) is not a condition for the validity of ablution because it is done to remove Najaasah(impurity), thus if there is no Najaasah, there is no need for that, and then it is permissible to make ablution without answering the call of nature. However, prayer is invalidated if there is Najaasah on the anus ,or the front opening, so it(Najaasah) must be removed for the prayer to become valid, and not the ablution.