Q: Somebody had nocturnal emission but he did not know that he became junub and he should have made a ghusl. Now should he make a ghusl and repeat all his prayers?
It is notable that he made ghusl every time he took a bath but with the intention of general purity and seeking nearness to Allah.
A: He has to make up in qaḍā’ all the prayers he offered in a state of janābah even though he was ignorant of janābah. Mere washing body cannot take the place of ghusl of janābah unless it is done with such an intention.
Anyhow, if he washed his body with the intention of a ghusl which he may have been to perform (whether obligatory or mustaḥabb), this can replace the ghusl of janābah.