What is the ruling on swearing an oath to compel a friend to take money in exchange for goods, after he had sworn not to take it?

It appears from your oath that you intended for your friend to take the money immediately. If he insisted on refusing and the money remained with you, then you have broken your oath and expiation is required of you, as Khalil ibn Ishaq stated: "And he has broken his oath if he had no intention, nor any indication, that what he swore about would be missed."