The ones who had been sent were from the Pharisees.

 He said: "I am baptizing only with water; but there is One among you--you don't recognize him--and I am not worthy to untie the straps of his shoes." John could not have cited a more menial office. To untie the straps of sandals was slaves' work. There was a Rabbinic saying which said that a disciple might do for his master anything that a servant did, except only to untie his sandals. That was too menial a service for even a disciple to render. So John said: "One is coming whose slave I am not fit to be." We are to understand that by this time the baptism of Jesus had taken place at which John had recognized Jesus. So here John is saying again: "The king is coming. And, for his coming, you need to be cleansed as much as any Gentile. Prepare yourself for the entry into history of the king." 