Is the saying, "I have believed in the Holy Qur’an and everything revealed therein, and everything mentioned therein, and in its rulings, and every word in the Holy Qur’an, and every letter therein," permissible and valid?

This phrase is correct in meaning, but its wording is not authentically transmitted and contains artificiality and redundancy. It is sufficient for a believer to say: "I have believed in the Book of Allah," as stated in the Hadith of Al-Bara' bin 'Azib: "I have believed in Your Book which You revealed and in Your Prophet whom You sent."