What is the ruling on lying under oath upon the Holy Quran to implicate an embezzler, and is expiation obligatory for that, knowing that the one who lied justifies his action by saying that he was compelled to do so for fear of dismissal from work?

Embezzling funds and deceitfully appropriating employee allowances are reprehensible and impermissible acts. Forging documents is a form of forbidden false testimony. Intentionally swearing a false oath is deplorable, whether it is sworn on the Qur’an or otherwise, though the sin is greater when sworn on the Qur’an. This is the "Al-Yamin Al-Ghamus" (the immersive oath), for which there is no expiation according to the majority of scholars. One must promptly initiate sincere repentance and resolve not to return to such matters. It is safer to offer expiation for the oath. If the wronged person incurred a greater material loss than they deserve, then what was taken from them must be returned, or their forgiveness must be sought.