Is it part of the Muslim creed to believe that sins are committed by prophets and that they are not infallible?

The prophets are infallible in conveying the religion from Allah Almighty; they do not conceal anything of what Allah has revealed to them, nor do they add anything to it from themselves. They are also infallible from major sins. As for minor sins, they may commit them, but they are not condoned for them; rather, Allah Almighty alerts them to these sins, and they promptly repent from them. They may also err in worldly matters that are not related to revelation, such as medicine and agriculture, and this is not done intentionally.