All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Taking a false oath is one of the grave sins that incurs the wrath of Allah the Almighty and one who does this for a worldly benefit barters that which is better (Islam) for that which is meaner (Worldly life). Allah the Exalted Says {What means}: "As for those who sell the faith they owe to God and their own plighted word for a small price, they shall have no portion in the Hereafter: Nor will God (Deign to) speak to them or look at them on the Day of Judgment, nor will He cleans them (of sin): They shall have a grievous penalty." {Al-Emraan, 77}. Moreover, Allah's Messenger (PBUH) says: "If anyone swears a firm oath - knowingly, intentionally, taking by it property belonging to a Muslim, Allah will be angry with him when he meets Him (on the Day of Resurrection)." [Agreed upon].
In addition, it is forbidden for the person who had committed this grave sin to take the money which he managed to obtain through lying, because the Messenger of Allah (PBUH) says: "Verily, I am only a human and the claimants bring to me (their disputes); perhaps some of them are more eloquent than others. I judge according to what I hear from them). So, he whom I, by my judgment, (give the undue share) out of the right of a Muslim, I in fact give him a portion of (Hell) Fire". {Agreed upon}.
If the judge found out, even after passing the sentence, that she had taken a false oath, she will receive worldly punishment while in the Hereafter this matter is up to Allah. However, if the judge didn`t know that then Allah Knows and He Will Give rights to whomever they belong on the Day of Judgment.
It is incumbent upon the person who had taken a binding oath falsely to rush to make sincere repentance, give back rights to whom they belong and it is permissible to give religious expiation, which is feeding ten needy persons, to be on the safe side as far as the teachings of Sharia are concerned. And Allah the Almighty Knows Best.