Hazrat Burd says that I asked Hazrat Zuhri when buying and selling become prohibited on Friday. He replied that previously, it used to be at the time of the first call to prayer when the Imam would come out. Then Hazrat Uthman added a third call to prayer, after which the call to prayer began to be given from the minaret to gather the people. In my opinion, buying and selling should be abandoned at that time.