It goes without saying that friendship matters more than work.
Literal
Friendship [subject-が] work [than-より] important [explanatory-な] [nominalizer-の] [topic-は] say [until-まで] [also-も] not-exist.
言うまでもない (literally 'there is not even up to saying') is a set phrase meaning 'it goes without saying.' The nominalized clause 友情が仕事より大切なの becomes the topic, and 言うまでもない is the comment.