What is the ruling regarding an employee who cannot leave his workplace to perform the prayer upon hearing the Adhan?

Performing the five daily prayers in congregation is obligatory for those who are able, and there are many proofs for this. Among them is the hadith of the blind man whom the Prophet, peace and blessings be upon him, permitted to pray in his house. The Prophet asked him, "Do you hear the call [to prayer]?" He said, "Yes." The Prophet said, "Then respond." This indicates the obligation to respond to the caller for anyone who hears the call, even if they are an employee.

However, if attending the congregation would result in the loss of the work entrusted to him, then he is considered among those with valid excuses permitted to miss congregational prayer. This is based on the hadith narrated by Ibn Abbas, may Allah be pleased with them both, from the Messenger of Allah, peace and blessings be upon him, who said: "Whoever hears the call [to prayer] and is not prevented from following it by an excuse..." They asked, "What is the excuse, O Messenger of Allah?" He said, "Fear or illness. Allah will not accept the prayer he prayed [alone]." This was narrated by Imam Ahmad and Al-Hakim.

The fear that is among the excuses for missing congregational prayer makes no distinction between fear for oneself and fear for one's property. A Muslim should not remain in a job that leads to missing congregational or Friday prayers unless absolutely necessary, and should search for an alternative job that does not lead to this.