What is incumbent upon one who swore that he did not do something which he had in fact done, and committed sodomy before repentance? Is expiation (kaffarah) obligatory upon him?

Whoever swears falsely that he did not commit an act which he did commit, has sworn a 'yamin ghamus' (a false oath taken knowingly), which is one of the gravest major sins. Likewise, sodomy is among the most heinous major sins. The expiation for this is sincere repentance to Allah and seeking His forgiveness, for Allah accepts repentance and pardons sins. As for swearing falsely, there is a difference of opinion among scholars as to whether it requires an expiation for an oath. It is more prudent to offer expiation for it, so as to avoid disagreement.