A great little blurb by Edmund Clowney in this oft overlooked little book:
As we preach the Word of God we are not clothed in apostolic authority. We cannot bear their eyewitness to the risen Christ. But by God’s grace we are numbered among those faithful men into whose hands the apostolic deposit has been placed. Like Timothy we must guard that good deposit through the Holy Spirit who dwelleth in us (II Tim. 1:14). We do so when we hold to the outline of sound words which we read in that Book which contains the witness of the apostles and is the Word of God.
Preaching and Biblical Theology, Pg. 61.