What is the Sharia ruling on a doctor delaying his return to his country after being sent abroad for two or three years to collect money to secure housing, and is he absolved if the state imposes a fine on him and he pays it?

It is not permissible to violate the covenant and agreement made with the sponsoring entity, because adherence to covenants is a religious obligation. One must be truthful in speech, fulfill promises, discharge trusts, and abide by covenants, as Allah the Almighty says: (O YOU WHO HAVE BELIEVED, FEAR ALLAH AND BE WITH THE TRUTHFUL), and (INDEED, ALLAH COMMANDS YOU TO RENDER TRUSTS TO WHOM THEY ARE DUE), and (AND THOSE WHO ARE TO THEIR TRUSTS AND THEIR COVENANT OBSERVERS). Furthermore, non-compliance inflicts harm upon the sponsoring entity, as it expended funds with the expectation that you would return and work for them, the consequences of which you bear. There is also a third caution, which is residing in a non-Muslim country, which is forbidden except out of necessity for studies not available in Muslim countries, and work is not considered an excuse to remain.