Ambrose (c. 339-97):
"Let God Himself, Who made me, teach me the mystery of heaven, not man, who knew not himself. Whom rather than God should I believe concerning God? NPNF2: Vol. X, The Letters of St. Ambrose, Letter 18, § 7.
Many times have the clergy erred; the bishop has wavered in his opinion; the rich men have adhered in their judgment to the earthly princes of the world; meanwhile the people alone preserved the faith entire. John Daillé, A Treatise on the Right Use of the Fathers (Philadelphia: Presbyterian Board of Publication, 1856), p. 197.
Latin text: Plerumque clerus erravit, Sacerdos mutavit sententiam, divites cum saeculi istius terreno rege senserunt; populus fidem propriam reservavit. In Psalmum David CXVIII Expositio, Sermo 17, §17, PL 15:1446.
On Psalm 1: Be not alarmed because the cup of Babylon is a golden cup, for you drink out of the cup of wisdom, which is more precious than gold and silver. Drink of each cup, therefore, of the Old and New Testament, because you drink of Christ from each. Drink Christ, that you may drink the blood with which you are redeemed: drink Christ, that you may drink his discourses. His discourse is the Old Testament; his discourse is the New Testament. The Holy Scripture is drunk and devoured, when the juice of the eternal Word descends into the veins and energies of the mind. Lastly, man lives not by bread alone, but by every word of God. Drink this word, but drink it in its right order. First drink it in the Old Testament, and make haste to drink it in the New Testament. George Finch, A Sketch of the Romish Controversy (London: G. Norman, 1831), pp. 220-222.
Latin text: Nec te moveat quod Babylonis aureum poculum est; quia et tu bibis poculum sapientiae, quae sit auro argentoque pretiosior. Utrumque ergo poculum bibe veteris et novi Testamenti; quia in utroque Christum bibis. Bibe Christum, quia vitis est, bibe Christum, quia petra est quae vomuit aquam; bibe Christum, quia fons vitae est, bibe Christum, quia flumen est, cujus impetus laetificat civitatem Dei; bibe Christum, quia pax est; bibe Christum, quia flumina de ventre ejus fluent aquae vivae; bibe Christum, ut bibas sanguinem quo redemptus es; bibe Christum, ut bibas sermones ejus; sermo ejus Testamentum est vetus, sermo ejus Testamentum est novum. Bibitur Scriptura divina, et devoratur Scriptura divina cum in venas mentis ac vires animae succus verbi descendit aeterni. Denique non in solo pane vivit homo, sed in omni verbo Dei. Hoc verbum bibe, sed ordine suo bibe. Primum bibe in veteri Testamento: cito fac ut bibas et in novo Testamento. Enarrationes In XII Psalmos, In Psalmum Primum Enarratio, §33, PL 14:939-940.
Commenting on ‘And whatsoever house ye enter into, there abide.’ (Lk. 9:4): So the faith of the Church must be sought first and foremost; if Christ is to dwell therein, it is undoubtedly to be chosen. But lest an unbelieving people or heretical teacher disfigure its habitation, it is enjoined that the fellowship of heretics be avoided and the synagogue shunned. The dust is to be shaken off your feet [cf. St. Luke 9:5], lest when the drynesses of barren unbelief crumble the sole of your mind it is stained as if by a dry and sandy soil. For a preacher of the Gospel must take upon himself the bodily weaknesses of a faithful people, so to speak, and lift up and remove from his own soles the worthless actions like to dust, according as it is written: “Who is weak, and I am not weak?” [II Corinthians 11:29]. Thus, any Church which rejects faith and does not possess the foundations of Apostolic preaching is to be abandoned, lest it be able to bespatter some stain of unbelief. This the Apostle also clearly affirmed, saying, “A man that is an heretic after the first admonition reject” [Titus 3:10]. Saint Ambrose of Milan, Exposition of the Holy Gospel according to Saint Luke, trans. Theodosia Tomkinson (Etna: Center for Traditionalist Orthodox Studies, 1998), Book VI, §68, pp. 216-217.
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.