"Love to read the sacred Letters, and you will not find many things to ask of me. By reading and meditating, if you pray wholeheartedly to God, the Giver of all good things, you will learn all that is worth knowing, or at least you will learn more under His inspiration than through the instruction of any man."
Source: FC, Vol. 20, Saint Augustine Letters, 140. Addressed to Honoratus (412 AD), Chapter 37 (New York: Fathers of the Church, Inc., 1953), pp. 135-136. Honoratus was a catechumen.
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.