Answer
(Fatwa: 184/H=183)
It is Wajib (necessary) to proceed for Juma Salah after first Azan is called. Therefore, sleeping or doing any transaction that interferes in the process is impermissible. Allah says:
O ye who believe! When the call is proclaimed to prayer on Friday, hasten earnestly to the remembrance of Allah, and leave off business; that is best for you if ye but knew! (The Quran, 62/9).
So, it is necessary on the first Azan to leave off business and hasten to Salah. (Durr-e-Mukhtar, 3/38)
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband