Are swearing by Allah falsely and swearing on the Qur'an without knowledge considered major sins, and what is the repentance for them?

Whoever swears by Allah falsely and intentionally has committed a grave sin, which worsens if the the oath was sworn upon the Mushaf. This is called al-Yamin al-Ghamus (the immersive oath), and it is one of the major sins. The majority of scholars hold that al-Yamin al-Ghamus cannot be expiated, and its perpetrator must only offer sincere repentance (tawbah nasuh). Whereas the Shafi'is are of the opinion that it can be expiated. The more cautious approach is for one to combine sincere repentance with performing the expiation for an oath, which is feeding ten poor persons, or clothing them, or emancipating a slave. If one cannot find [any of these], then fasting for three days. Swearing by the Mushaf is considered a binding oath (yamin mun'aqidah) by the general body of scholars. Sincere repentance erases what came before it.