What is the evidence from the Qur’an and Sunnah that Sheikh Abu Ali al-Mashdali relied upon to rule that a man whose wife goes out and conducts her affairs with her face and limbs exposed is not permitted to lead prayers (Imamah) and his testimony is not accepted, and when is a man's Imamah not permitted and his testimony not accepted?

Sheikh Abu Ali Mansour al-Mashaddali (died 731 AH) issued a fatwa that it is impermissible for a man whose wife goes out with her face and limbs uncovered to lead prayers, and that his testimony is not acceptable. This fatwa is based on two matters: First: That this husband has lost his moral uprightness (adalah) because he allowed his wife to go out unveiled and intermingling, which is among the greatest fitan (trials/temptations) and abominations. Second: That whoever has lost his moral uprightness due to فسق (disobedience/immorality), his imamate (leading prayers) is not valid, and his testimony is not accepted, due to suspicion of his leniency in fulfilling religious obligations.