Dr Abd Al Haleem Mahmoud- may Allah have mercy on him- says:
Allah SWA says: (O you who have believed, when [the adhan] is called for the prayer on the day of Jumu’ah [Friday], then proceed to the remembrance of Allah and leave trade. That is better for you, if you only knew.)
This great verse shows the stance of Islam on the call to the Friday prayer. Selling is like the things that keep a person busy at the call for Friday prayer and the question is not solely about selling, it is for everything which keeps a person busy, and the verse is clear in its meaning. The Friday prayer in the correct circumstances does not take a lot of time, for the sermon and the prayer. The moment it ends the person returns to his work, and on this Allah SWA says: (And when the prayer has been concluded, disperse within the land and seek from the bounty of Allah, and remember Allah often that you may succeed.)
Some people whose faith have not reached the deepest of their hearts may leave a part of the Friday prayer to go and do something else, and Allah SWA warns them about this saying: (But when they saw a transaction or a diversion, [O Muhammad], they rushed to it and left you standing. Say, “What is with Allah is better than diversion and than a transaction, and Allah is the best of providers.”) The Friday prayer has no replacement if one who is able to perform it ignores it without any legally accepted reason.