Tertullian, Prescription against Heretics 26
It followed necessarily that when Christ entrusted the administration of the Gospel, He attached a condition drawn from His own voice: it must not be dispensed randomly or thoughtlessly, lest they cast a pearl before pigs and throw something holy to dogs (Matt 7:6). The Lord declared this openly, without any hint of a hidden sacrament. He Himself had commanded that whatever they heard in darkness and in secret, they must preach in the light and from the housetops. He Himself had illustrated through a parable that they must not hoard a single mina — that is, a single word of His — without fruit, locked away in secret. He Himself taught that a lamp is not hidden under a bushel but set on a stand, so that it shines for everyone in the house (Mark 4:21-22). The Apostles either ignored these commands or failed utterly to grasp them, if they did not carry them out by concealing something of the light — that is, of God's word and Christ's sacrament.
As far as I know, they feared no one — not the violence of the Jews, not the Gentiles. All the more, then, they preached freely in the Church, precisely because they did not keep silent in synagogues and public places. Indeed, they could never have converted Jews or won over Gentiles unless they set out in order what they wanted people to believe; much more, then, would they not have withheld anything from the believing Churches that they might have entrusted separately to a few. True, they may have discussed certain matters among their own people, so to speak, but it is not to be believed that those discussions introduced another rule of faith, different from and contrary to what the Catholic Church proclaimed openly — so that they would name one God in church and another at home, designate one substance of Christ in public and another in secret, announce one hope of resurrection to all and another to a few. After all, they themselves pleaded in their Epistles that everyone speak the same thing and that there be no schisms or dissensions in the Church, because whether it was Paul or others, they all preached the same message. Otherwise they remembered the command: Let your word be 'yes, yes; no, no'; anything beyond this comes from evil (Matt 5:37) — lest, that is, they treat the Gospel in diversity.
Latin
Porro consequens erat, ut cui demandabat Evangelii administrationem, non passim, nec inconsiderate administrandam, adjiceret secundum dominicam vocem, ne margaritam porcis, et sanctum canibus jactaret. Dominus palam edixit, sine ulla significatione alicujus tecti sacramenti. Ipse praeceperat, si quid in tenebris et in abscondito audissent, in luce et in tectis praedicarent. Ipse per similitudinem praefiguraverat, ne unam mnam, id est unum verbum ejus, sine fructu in abdito reservarent. Ipse docebat, lucernam non sub modio abstrudi solere, sed in candelabrum constitui, ut luceat omnibus qui in domo sunt. Haec Apostoli, aut neglexerunt, aut minime intellexerunt, si non adimpleverunt abscondentes aliquid de lumine, id est, de Dei verbo et Christi sacramento. Neminem quod scio verebantur, non Judaeorum vim, non ethnicorum; quo magis utique in Ecclesia libere praedicabant, qui in synagogis et in locis publicis non tacebant. Imo neque Judaeos convertere, neque ethnicos inducere potuissent, nisi quod credi ab eis volebant ordine exponerent: multo magis jam credentibus Ecclesiis nihil subtraxissent, quod aliis paucis seorsum demandarent. Quanquam, etsi quaedam inter domesticos, ut ita dixerim, disserebant, non tamen ea fuisse credendum est, quae aliam regulam fidei superducerent, diversam et contrariam illi, quam Catholicae in medium proferebant; ut alium Deum in ecclesia dicerent, alium in hospitio; aliam Christi substantiam designarent in aperto, aliam in secreto; aliam spem resurrectionis apud omnes annuntiarent, aliam apud paucos: cum ipsi obsecrarent in Epistolis suis, ut idipsum et unum loquerentur omnes, et non essent schismata et dissensiones in Ecclesia, quia sive Paulus, sive alii, eadem praedicarent. Alioquin meminerant: Sit sermo vester, est, est; non, non; quod amplius, hoc a malo est; ne scilicet Evangelium in diversitate tractarent.