What is the ruling on a pharmacist selling medicine during the Friday sermon, and what are the consequences if it is deemed invalid?

Selling is forbidden after the second call to prayer on Friday, which is after the preacher ascends the pulpit, due to the Almighty's saying: ﴿O YOU WHO HAVE BELIEVED, WHEN [THE ADHAN] IS PROCLAIMED FOR THE PRAYER ON THE DAY OF JUMU‘AH, THEN HASTEN TO THE REMEMBRANCE OF ALLAH AND LEAVE TRADE.﴾ The majority of jurists hold that the sale is valid despite its prohibition, while the Hanbalis consider the sale void. This applies unless there is a necessity or need, such as buying food or drink for someone in dire need. If the sale has occurred, it is sufficient to follow the opinion of the majority and repentance suffices.