What is the ruling on the ritual bath and prayers of one who did not rinse his mouth or sniff water into his nose during ghusl, knowing that he used to follow the Hanafi school of thought, believing that this conformed to their madhhab, and he now follows the preponderant opinion?

An ordinary person has no madhhab; rather, his madhhab is that of his mufti, because he lacks knowledge of the evidences or insight into the madhhab. His mere statement, "I am a Hanafi," does not make him one. Accordingly, a person who does not know that rinsing the mouth and sniffing water into the nose are obligatory in ghusl according to the Hanafis cannot be considered a Hanafi in this matter, because its ruling has not reached him. The preponderant opinion is that rinsing the mouth and sniffing water into the nose are Sunnah acts in ghusl, which is the view of the Shafi'is and Malikis. Based on this, the prayers of the aforementioned person are valid, and he is not required to repeat them.