5a] Is it permissible for him to complete the purchase when he can hear the call to prayer?

''Friday Prayers'' :-:->
5a]
To sum up: Jumu'ah cannot be compared with other prayers, but if he
avoids such situations so that he will not be distracted from praying
incongregation, that is better.
Whatever the case, if his buying and selling may distract him from
performing prayer in congregation, then it is haraam, but in some
casesthe prayer may be delayed, if the Imam is late, so a person may
buy or sell something on his way, and it may not affecthis attending
the prayer. But if he avoids that and adheres to what applies to
Jumu'ah, that will be more on the safe side, so it is like Jumu'ah
with regard to precautions.

And Allah knows best.