What is the ruling on the prayer of one who did not perform istinjāʾ during fasting despite needing to, and is istinjāʾ permissible during fasting?

We thank the questioner for her question, for shyness is blameworthy in matters of religion. It is stipulated by the Shafi'is that what is obligatory upon a woman in istinja' (washing after relieving oneself) with water is to wash what becomes visible from her when she sits on her heels. It is commendable for her to wash what is easily accessible from the inner part of her private parts without exaggeration or believing it to be obligatory. The entry of water into the stomach does not affect fasting. The discharges from a woman's private parts nullify wudu' (ablution), but they are pure, so istinja' is not obligatory from them, although it is better to perform istinja' for purification and removal of filth.