Islamic ruling on oaths

If this was a valid oath and it is now being broken, then kaffarah (expiation) is required. The kaffarah for an oath is to feed ten needy people or provide them with clothing. If one is unable to do this, then three consecutive days of fasting should be observed.

Simply saying, “I am young,” does not cause the kaffarah to be waived. However, if you are legally considered a minor (not yet mature according to Islamic law), then your oath was not validly binding in the first place, let alone requiring kaffarah.

And Allah knows best.