What is incumbent upon me by way of expiation for breaking my oath by Allah upon the Noble Qur’an to abandon masturbation?

You must repent sincerely, seek much forgiveness, and do good deeds. You also owe expiation for your oath by feeding ten needy persons from the average of what you feed your families, or clothing them, or freeing a slave. If you are unable to do that, then fast for three days, as Allah Almighty says: (Allah will not impose blame upon you for what is unintentional in your oaths, but He will impose blame upon you for what you intended of oaths; so its expiation is the feeding of ten needy people from the average of that which you feed your [own] families or clothing them or freeing a slave. But he who finds not [the means to do so] - then a fast of three days [is required]. That is the expiation for oaths when you have sworn. And guard your oaths). Swearing by the Mushaf (Qur’an) or in a virtuous place is for the glorification and confirmation of the oath, and it has no effect on the expiation. You must abandon masturbation due to its prohibition and numerous harms.