Q: Assuming one wakes up, before fajr, in a state of nocturnal emission, may
he/she not ghuslate oneself until moments before the fajr adhan and thus
tayammumate instead?
A: Assuming one intentionally delays ghuslating until there remains limited time
to ghuslate, he/she would have sinned. Nevertheless, he/she ought to tayammumate
before fajr arrives and his/her fast will be deemed valid.