Before 1st Vatican Council, the Church’s Pope have always practice infallibility.
“The Church of God which sojourns in Rome to the Church of God which sojourns in Corinth…If anyone disobey the things which have been said by Him through us, let them know that they will involve themselves in transgression and in no small danger.” Pope Clement of Rome [regn. c A.D.91-101], 1st Epistle to the Corinthians, 1,59:1 (c. A.D. 96).
“Thereupon Victor, who presided over the church at Rome, immediately attempted to cut off from the common unity the parishes of all Asia, with the churches that agreed with them, as heterodox; and he wrote letters and declared all the brethren there wholly excommunicate…” Pope Victor I [regn. A.D. 189-198], in Eusebius EH, 24:9 (A.D. 192).
“Stephen, that he who so boasts of the place of his episcopate, and contends that he holds the succession from Peter, on whom the foundations of the Church were laid…Stephen, who announces that he holds by succession the throne of Peter.” Pope Stephen I [regn. A.D. 254-257], Firmilian to Cyprian, Epistle 74/75:17 (A.D. 256).
“I beseech you, readily bear with me: what I write is for the common good. For what we have received from the blessed Apostle Peter s, that I signify to you; and I should not have written this, as deeming that these things were manifest unto all men, had not these proceedings so disturbed us.” Pope Julius [regn. A.D. 337-352], To the Eusebians, fragment in Athanasius’ Against the Arians, 2:35 (c. A.D. 345).
“Why then do you again ask me for the condemnation of Timotheus? Here, by the judgment of the apostolic see, in the presence of Peter, bishop of Alexandria, he was condemned, together with his teacher, Apollinarius, who will also in the day of judgment undergo due punishment and torment. But if he succeeds in persuading some less stable men, as though having some hope, after by his confession changing the true hope which is in Christ, with him shall likewise perish whoever of set purpose withstands the order of the Church. May God keep you sound, most honoured sons.” Pope Damasus [regn. A.D. 366-384], To the Eastern Bishops, fragment in Theodoret’s EH, 5:10 (c. A.D. 372).
“We bear the burdens of all who are heavy laden; nay, rather, the blessed apostle Peter bears them in us and protects and watches over us, his heirs, as we trust, in all the care of his ministry…Now let all your priests observe the rule here given, unless they wish to be plucked from the solid, apostolic rock upon which Christ built the universal Church…I think, dearest brother, disposed of all the questions which were contained in your letter of inquiry and have, I believe, returned adequate answers to each of the cases you reported by our son, the priest Basianus, to the Roman Church as to the head of your body…And whereas no priest of the Lord is free to be ignorant of the statutes of the Apostolic See and the venerable provisions of the canons.” Pope Sircius [regn. c A.D. 384-399], To Himerius, bishop of Tarragona (Spain), 1,3,20 (c. A.D. 392).
“Care shall not be lacking on my part to guard the faith of the Gospel as regards my peoples, and to visit by letter, as far as I am able, the parts of my body throughout the divers regions of the earth.” Pope Anastasius [regn. A.D. 399-401], Epistle 1 (c. A.D. 400).
“In making inquiry with respect to those things that should be treated … by bishops … as you have done, the example of ancient tradition … For you decided that it was proper to refer to our judgment, knowing what is due to the Apostolic See, since all we who are set in this place, desire to follow that Apostle from whom the very episcopate and whole authority of this named derived … that whatsoever is done, even though it be in distant provinces, should not be ended without being brought to the knowledge of this See, that by its authority the whole just pronouncement should be strengthened, and that from it all other Churches (like waters flowing from their natal source and flowing through the different regions of the world, the pure streams of one incorrupt head)…you also show your solicitude for the well being of all, and that you ask for a decree that shall profit all the Churches of the world at once.” Pope Innocent I [regn. A.D. 401-417], To the Council of Carthage, 1,2 (A.D. 417).
“It is therefore with due care and propriety that you consult the secrets of the Apostolic office that office, I mean, to which belongs, besides the things which are without, the care of all the Churches…Especially as often as a question of faith is discussed, I think that all our brothers and fellow bishops should refer to none other than to Peter, the author of their name and office.” Pope Innocent I [regn. A.D. 401-417], To the Council of Mileve, 2 (A.D. 417).
“Although the tradition of the fathers has attributed to the Apostolic See so great authority that none would dare to contest its judgment, and has preserved this ever in its canons and rules, and current ecclesiastical discipline in its laws still pays the reverence which it ought to the name of Peter…For he himself has care over all the churches, and above all of that which he sat…Since, then Peter is the head of so great authority, and has confirmed the suffrages of our forefathers since his time…and as bishops you are bound to know it; yet; though such was our authority that none could reconsider our decision.” Pope Zosimus [regn. A.D. 417-418], To the Council of Carthage (c. A.D. 418).
