[Thanks to A Year with the Church Fathers for the tip]
It is one and the same God Whom both the Old and the New Testament proclaim, Who is praised and glorified in the Trinity: I am come, saith the Lord, not to destroy the law but to fulfil it (St. Mt. v. 17.). For He Himself worked out our salvation for which all Scripture and all mystery exists. And again, Search the Scriptures for they are they that testify of Me (St. John v. 39.). And the Apostle says, God, Who at sundry times and in diverse manners spake in time past unto the fathers by the prophets, hath in these last days spoken unto us by His Son (Heb. i. 1, 2.). Through the Holy Spirit, therefore, both the law and the prophets, the evangelists and apostles and pastors and teachers, spake.
All Scripture, then, is given by inspiration of God and is also assuredly profitable (2 Tim. iii. 16.). Wherefore to search the Scriptures is a work most fair and most profitable for souls. For just as the tree planted by the channels of waters, so also the soul watered by the divine Scripture is enriched and gives fruit in its season (Ps. i. 3.), viz. orthodox belief, and is adorned with evergreen leafage, I mean, actions pleasing to God. For through the Holy Scriptures we are trained to action that is pleasing to God, and untroubled contemplation. For in these we find both exhortation to every virtue and dissuasion from every vice. If, therefore, we are lovers of learning, we shall also be learned in many things. For by care and toil and the grace of God the Giver, all things are accomplished. For every one that asketh receiveth, and he that seeketh findeth, and to him that knocketh it shall be opened (St. Luke xi. 10.). Wherefore let us knock at that very fair garden of the Scriptures, so fragrant and sweet and blooming, with its varied sounds of spiritual and divinely-inspired birds ringing all round our ears, laying hold of our hearts, comforting the mourner, pacifying the angry and filling him with joy everlasting: which sets our mind on the gold-gleaming, brilliant back of the divine dove (Ps. lxviii. 13.), whose bright pinions bear up to the only-begotten Son and Heir of the Husbandman (St. Matt. xxi. 37) of that spiritual Vineyard and bring us through Him to the Father of Lights (Jas. i. 17.). But let us not knock carelessly but rather zealously and constantly: lest knocking we grow weary. For thus it will be opened to us. If we read once or twice and do not understand what we read, let us not grow weary, but let us persist, let us talk much, let us enquire. For ask thy Father, he saith, and He will shew thee: thy elders and they will tell thee (Deut. xxxii. 7.). For there is not in every man that knowledge (1 Cor. viii. 7.). Let us draw of the fountain of the garden perennial and purest waters springing into life eternal (St. John iv. 14.). Here let us luxuriate, let us revel insatiate: for the Scriptures possess inexhaustible grace. (St. John of Damascus [d. 749], An Exact Exposition of the Orthodox Faith, 4.17 [http://www.ccel.org/ccel/schaff/npnf209.iii.iv.iv.xvii.html])