Is it ensure, insure, or assure?
1610s, "means of supplying a want or deficiency," from French resourse "a source, spring," noun use of fem. past participle of Old French resourdre "to rally, raise again," from Latin resurgere "rise again" (see resurgent). Resources "a country's wealth" first recorded 1779.
1975, from resource (n.). Related: Resourced; resourcing.