Does expiation become obligatory for one who swore not to take his share of the inheritance, then took it, donated part of it, and kept the rest?

You owe an expiation for breaking an oath (kaffarat yamin) because you violated your قسم (oath) by taking what you swore not to take. The expiation for breaking an oath is to feed ten poor people, or clothe them, or free a slave. If you cannot find any of these, then you must fast for three days. There is no blame on you for breaking the oath if you see that taking your share is better for you, due to the saying of the Prophet, peace and blessings be upon him: "By Allah, I will not swear an oath and then see something better than it except that I will do that which is better and release myself from the oath."