What is the expiation for one who swore falsely to obtain a certificate matching his original certificate, without harming anyone, while a worldly benefit resulted from it?

When a Muslim enters a land of disbelievers with their permission, he must fulfill the agreed-upon conditions, as long as they do not involve disobedience to Allah. The jurists have agreed on the obligation not to betray or deceive those who enter the land of war under a pledge of safety. This is supported by Allah’s saying: ﴿O YOU WHO HAVE BELIEVED, FULFILL [ALL] CONTRACTS﴾, and the Prophet's (peace be upon him) saying: "Muslims are bound by their conditions." A Muslim must not swear falsely, especially if this oath leads to taking money or education that he does not deserve, as this is one of the major sins. Sustenance is only obtained through what Allah Almighty has made lawful, and sustenance must be sought through legitimate means, without hastening it by disobeying Allah.