Is Scripture the sole rule of faith for Christians? Not according to the Bible. While we must guard against merely human tradition, the Bible contains numerous references to the necessity of clinging to apostolic tradition.
"If you should acknowledge and love Christ you would give up not only all the treasures of this life, but even the glory of your crown itself to win eternal life."
~ Pope Urban II, at the Council of Benevento (A.D. 1091); explaining the boundaries of Holy Orders as set forth in Holy Scripture and in the authentic writings of the Apostolic Fathers (from the article "Subdeacon")