Clement of Rome (c. 96):
"Ye are fond of contention, brethren, and full of zeal about things which do not pertain to salvation. Look carefully into the Scriptures, which are the true utterances of the Holy Spirit. Observe that nothing of an unjust or counterfeit character is written in them."
Source: ANF: Vol. I, The Apostolic Fathers, First Epistle of Clement to the Corinthians, Chapter 45.
"Ye understand, beloved, ye understand well the Sacred Scriptures, and ye have looked very earnestly into the oracles of God. Call then these things to your remembrance."
Source:ANF: Vol. I, The Apostolic Fathers, First Epistle of Clement to the Corinthians, Chapter 53.
For an excellent compilation of quotes of the Church fathers teaching on the primacy, sufficiency and ultimate authority of Scripture, get a copy of Holy Scripture:The Ground and Pillar of Our Faith Vol III- The Writings of the Church Fathers Affirming the Reformation Principle of Sola Scriptura.