Is expiation obligatory for one who swore an oath while angry and did not do what he swore to do?

There is no expiation for someone who swore not to do something and then did not do it, because they did not break their oath. If what was sworn to be abandoned was legally forbidden or permissible, then they were right in fulfilling their oath. But if it was a good deed, then it is better to expiate for their oath and do the good deed, for Allah Almighty says: ﴿And do not make [your oath by] Allah an obstacle against your doing good and fearing Allah and bringing about reconciliation among people﴾ [Al-Baqarah: 224], and for His saying, peace and blessings be upon him: "By Allah, if Allah wills, I do not swear an oath and then see something else better than it, except that I do what is better and release myself from it," and "If you swear an oath and then see something else better than it, then do what is better and expiate for your oath."