Ḥanbal said, in his account of al-Wāthiq’s reign: “The jurists of Baghdad gathered with Abū ʿAbd Allāh and said, ‘This matter has grown grave and spread widely’—by which they meant the public proclamation that the Quran was created—‘and we have come to consult you because we do not accept his authority or rule.’ He replied: ‘You must denounce it in your hearts, but do not abandon obedience, and do not divide the unity of the Muslims.’
According to the report of al-Marwazī, he mentioned al-Ḥasan ibn Ṣāliḥ and said: “He advocated armed revolt, and we do not approve of his doctrine.”
If the impairment that arises affects his body, the matter must be examined. If it is a loss of reason, then if it is a temporary condition likely to pass, such as unconsciousness, it does not prevent the conclusion of the imamate contract or its continuation, because it is an illness of short duration, and because the Prophet (peace and blessings be upon him) lost consciousness during his illness.
If, however, it is a permanent condition whose disappearance is not expected, such as insanity or mental derangement, then further distinction is required. If it is continuous, with no periods of lucidity, it prevents both his appointment and his continuation in office. If it arises after the imamate has been conferred, it invalidates it, because it prevents the purpose of the office—namely, enforcing the prescribed penalties, securing rights, and protecting the Muslims.
If the condition alternates with periods of lucidity in which he returns to a sound state, then if he spends most of his time in a state of mental derangement, it is treated as continuous. If he spends most of his time lucid, one view holds that it prevents the conclusion of the imamate contract. As for whether it prevents his continuation in office, it has been said that it does, just as it prevents his initial appointment, because it compromises the governance required of him. It has also been said that it does not prevent his continuation, even though it prevents his initial appointment, because complete soundness is required when the imamate contract is first concluded, whereas complete incapacity is required for removal from office.
As for loss of sight, it prevents both the conclusion of the imamate contract and its continuation, because it invalidates his serving as a judge and prevents him from being an admissible witness; all the more, then, should it prevent the validity of the imamate. As for night blindness—that is, being unable to see when night begins—it does not prevent the conclusion of the imamate contract or its continuation, because it is an illness confined to a time of rest, and its disappearance may be hoped for.
As for weak eyesight, if he can recognize people when he sees them, it does not prevent him from serving as imam. But if he can perceive people without recognizing them, it prevents both the conclusion of the imamate contract and its continuation. If he cannot smell because of a defect in his nose, or if he has lost his sense of taste so that he cannot distinguish flavors, this does not affect the conclusion of the imamate contract, because these impair pleasure, not judgment or action.
Deafness and muteness prevent the initial conclusion of the imamate contract, because they affect governance and functioning just as blindness does. As for continuation in office, it has been said that they do not require his removal from the imamate, since gestures can serve in their place. Thus, complete soundness is required when the imamate is first conferred, whereas complete incapacity is required for removal from it.
Stammering and impaired hearing, when he can perceive sound if it is sufficiently loud, do not prevent either initial appointment or continuation in office. For Moses, Allah’s Prophet (peace be upon him), was not prevented from prophethood by his speech impediment; therefore, it is even less likely to prevent the imamate.
If his penis and testicles have been removed, this does not prevent him from becoming imam or from remaining in office, because the loss of these affects procreation, not judgment or movement. It is therefore analogous to impotence. Allah Most High described John, son of Zechariah (peace be upon them both), in these terms and praised him, saying: “A leader, chaste, and a prophet from among the righteous.” Ibn ʿAbbās (may Allah be pleased with them both) is reported to have said: “He had no penis with which to have intercourse with women; it was like a date stone.” Since this did not prevent him from prophethood, it is even more appropriate that it should not prevent him from the imamate.