Is swearing on the Qur'an not to do something that is not currently being done, knowing that it is usually done, considered a false oath (yamin ghamus), and what is its expiation, based on the saying of the Prophet, peace and blessings be upon him: "Deeds are only by intentions"?

If you swore falsely to your father that you did not do something you actually did, this is an oath (yamin ghamus) and its expiation is repentance and seeking forgiveness. However, if by the oath you intended a specific time during which you did not do that thing (tawriya - dissimulation), then there is nothing upon you, unless it leads to the nullification of a right or the establishment of falsehood. Tawriya is permissible to avoid lying, but it is not permissible in an absolute sense, and its rulings and regulations vary depending on the situation.