Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
errand [ˈɛrənd] n поруче́ние
to run errands выполня́ть (impf) поруче́ния
errand of mercy пое́здка*с до́брой ми́ссией
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.