Albert Barnes Commentary Matthew 11:7

"And as these went their way, Jesus began to say unto the multitudes concerning John, What went ye out into the wilderness to behold? a reed shaken with the wind?" — Matthew 11:7 (ASV)

And as they departed. Jesus took occasion, from the inquiries made by John's disciples, to instruct the people concerning John's true character. Multitudes had gone out to hear John when he preached in the desert (Matthew 3). It is probable that many had been attracted by the novelty of his appearance or doctrines, and that many others had gone simply to see and hear a man of unusual habits and opinions. Probably, many who followed Christ had been among that number. Jesus, therefore, took this occasion, using some striking questions, to examine the motives that had drawn them to John's ministry.

A reed shaken with the wind? The region in which John preached, being overflowed annually by the Jordan, produced great quantities of reeds, or canes, of a light, fragile nature, easily shaken by the wind. They were therefore an image of a fickle, changing, inconstant man. John's sending to Christ to inquire about Christ's character might have led some to suppose that John was changing and inconstant, like a reed. He had once acknowledged Christ to be the Messiah; and now, being in prison and sending to him to seek confirmation, they might have supposed that John had no firmness or fixed principles. Jesus, by asking this question, declared that, despite this appearance, this was not John's character.