It was narrated that Ibn ‘Abbas (رضي الله عنه) said:

The Messenger of Allah (ﷺ) forbade intercepting the riders (incoming traders) and forbade townspeople selling on behalf of a Bedouin. He (the narrator) said: I said to Ibn 'Abbas, what does “townspeople selling on behalf of Bedouin" mean? He said: He should not be a broker for him.