It is remarkable that those who go furthest in asserting the Messenger’s infallibility—may Allah bless him and grant him peace—are often the groups furthest removed from believing his reports and obeying his commands. Such are the Rāfidah, the Jahmiyyah, and similar groups, who go to extremes regarding their infallibility, yet reject his reports. Everyone who believes in the Messenger agrees that he is protected from error in what he conveys from Allah: no error persists in his reports, just as no falsehood occurs in them. The presence of either would contradict the purpose of his mission and the evidence establishing that he is a messenger.
As for his actions unrelated to conveying revelation from Allah, people disagree about his infallibility in these matters and draw various distinctions; this is not the place to discuss them. They also disagree over whether protection from error in such matters is known through reason or revelation. By contrast, his infallibility in conveying revelation is agreed upon and is known through both revelation and reason.
The purpose of conveying revelation is that he should be believed in what he reports and obeyed in what he commands. Anyone whose fundamental position is that evidence from revelation does not yield certainty, or who gives precedence to his own opinion and subjective intuition over the Messenger’s reports, gains no benefit from affirming the infallibility upon which all agree, much less from affirming it in the disputed matters. Rather, such people exalt the Messenger in matters outside the purpose of his mission, while failing to receive from him what his mission was intended to convey. In this respect, they have become like the Christians in their relationship with the Messiah, peace be upon him, who was sent to them: they did not receive from him the religion with which he was sent, but went to such extremes concerning him that they became guilty of associating him with Allah in worship, rather than believing in him.
Likewise, those who go to extremes concerning the prophets, the Prophet’s household, and the shaykhs associate them with Allah in worship rather than following what they report and command. Thus, they have departed from the true meaning of the testimony that there is no god but Allah and that Muhammad is the Messenger of Allah.