Does the failure of water to reach a part of the male organ—due to faulty circumcision—affect the validity of ritual purification (Tahara) and ritual bathing (Ghusl), and is it obligatory to repeat past prayers?

The prescribed circumcision for a man involves cutting the foreskin that covers the glans, such that the entire glans becomes exposed. If this is not achieved, then the remaining part of the foreskin must be cut, unless doing so would cause harm, as mentioned by An-Nawawi in Al-Majmoo‘. The retention of a part of the foreskin does not invalidate the prayer. However, the area from which water recedes during istinja (washing after relieving oneself) and ghusl (ritual bath) must be purified, because the presence of some foreskin is a potential site for the accumulation of impurities beneath it.