Albert Barnes Commentary Acts 21:22

"What is it therefore? They will certainly hear that thou art come." — Acts 21:22 (ASV)

What is it therefore? What is to be done? What is it proper to do to avoid the effects of the evil report that has been circulated? What they deemed proper to do is suggested in the following verses.

The multitude. The multitude of Jews.

Must needs come together (Acts 19:32). A tumultuous assembly will inevitably occur, and it will be impossible to prevent that.

There were several reasons for this. First, their minds were exceedingly agitated that one of their own countrymen had, as they understood it, been advising apostasy from the religion of their fathers. Second, this had been done extensively and with great success in many parts of the world. Third, Paul himself—having, as they believed, apostatized from the national religion—had become very prominent, and consequently, his very presence in Jerusalem, just as in other places, was likely to incite a tumult.

It was, therefore, an act of friendship to him and to the cause to devise some suitable plan to prevent, if possible, the anticipated excitement.