Who said the statement: "Virtue is more important than knowledge," and what does it mean?

The author of the phrase "Knowledge is virtue, and witnessing it is conduct" has not been found. It is probable that "virtue" here refers to the fruit of knowledge, as knowledge can exist without being acted upon. Virtue is the fruit of knowledge and acting upon it, and witnessing it is conduct. Some scholars interpret virtue as moderation and balance, such as Al-Shirazi, who sees it as the middle ground between excess and deficiency, confirming the Prophet’s (peace be upon him) saying: "The best of matters are their middles." Knowledge can also be a detriment to its possessor if it exceeds the bounds of reason and custom, and this leads to ruin. Virtue is moderation and avoiding extravagance and negligence. A scholar might go to extremes or fall short, but if they are characterized by virtue and moderation, they would not be so. Virtue is the middle ground between excess and deficiency, meaning moderation in every matter without exaggeration or neglect.