1) Clement of Rome (AD 96)
Most scholars believe that Clement of Rome wrote the letter called 1 Clement in 96 AD. In that letter, he quotes a significant portion of the book of Hebrews.
1 Clement 36:1-6 This is the way, dearly beloved, wherein we found our salvation, even Jesus Christ the High priest of our offerings, the Guardian and Helper of our weakness. 2 Through Him let us look steadfastly unto the heights of the heavens; through Him we behold as in a mirror His faultless and most excellent visage; through Him the eyes of our hearts were opened; through Him our foolish and darkened mind springeth up unto the light; through Him the Master willed that we should taste of the immortal knowledge Who being the brightness of His majesty is so much greater than angels, as He hath inherited a more excellent name. 3 For so it is written Who maketh His angels spirits and His ministers aflame of fire. 4 but of His Son the Master said thus, Thou art My Son, I this day have begotten thee. Ask of Me, and I will give Thee the Gentiles for Thine inheritance, and the ends of the earth for Thy possession. 5 And again He saith unto Him Sit Thou on My right hand, until I make Thine enemies a footstool for Thy feet. 6 Who then are these enemies? They that are wicked and resist His will.
From this, we can definitively say that the book of Hebrews was written no later than 96 AD, since that’s when Clement quoted it. Unfortunately, Clement didn’t give any other clues regarding who wrote the book.
2) Eusebius (AD 325)
Eusebius remarks that even in his day, some among the Romans didn’t consider Hebrews to be the Apostle Paul’s but he himself considers it genuinely Pauline.
Ecclesiastical History 6.20.3 There has reached us also a dialogue of Caius, a very learned man, which was held at Rome under Zephyrinus, with Proclus, who contended for the Phrygian heresy. In this he curbs the rashness and boldness of his opponents in setting forth new Scriptures. He mentions only thirteen epistles of the holy apostle, not counting that to the Hebrews with the others. And unto our day there are some among the Romans who do not consider this a work of the apostle.
Ecclesiastical History 3.3.5 Paul’s fourteen epistles are well known and undisputed. It is not indeed right to overlook the fact that some have rejected the Epistle to the Hebrews, saying that it is disputed by the church of Rome, on the ground that it was not written by Paul. But what has been said concerning this epistle by those who lived before our time I shall quote in the proper place. In regard to the so-called Acts of Paul, I have not found them among the undisputed writings.
Eusebius also mentions several other earlier testimonies regarding the book of Hebrews.
A) Caius (Gaius) of Rome (AD 200)
(See earlier reference – EH 6.20.3 – Caius did not see Hebrews as Pauline)
Note: Many scholars believe the Muratorian Canon (c. AD 170) was written by Caius. The MC does not list Hebrews as either canonical or Pauline.
B) Clement of Alexandria (AD 150-215)
Clement believed Hebrews was written by Paul in the Hebrew language, then translated into Greek by Luke. He said Paul didn’t prefix his normal introductory greeting because his audience was suspicious of Paul and he didn’t want to turn them away from the beginning.
Ecclesiastical History 6.14.2-3 He says that the Epistle to the Hebrews is the work of Paul, and that it was written to the Hebrews in the Hebrew language; but that Luke translated it carefully and published it for the Greeks, and hence the same style of expression is found in this epistle and in the Acts. 3 But he says that the words, Paul the Apostle, were probably not prefixed, because, in sending it to the Hebrews, who were prejudiced and suspicious of him, he wisely did not wish to repel them at the very beginning by giving his name.
David Allen, Hebrews, 30, notes that Clement was a student of Pantaenus, who ascribed Hebrews to Paul. Allen does not give a citation in this regard, though, and I was not able to track down this reference.
C) Origen (AD 184-253)
Eusebius also quotes Origen, who also argued for Pauline influence of Hebrews but not necessarily Pauline wording. Origen notes that Clement of Rome and Luke are also posited as authors of Hebrews by some, but he then famously says that God alone knows who wrote the book.
Ecclesiastical History 6.25.11-14 In addition [Origen] makes the following statements in regard to the Epistle to the Hebrews in his Homilies upon it: That the verbal style of the epistle entitled ‘To the Hebrews,’ is not rude like the language of the apostle, who acknowledged himself ‘rude in speech’ that is, in expression; but that its diction is purer Greek, anyone who has the power to discern differences of phraseology will acknowledge. 12 Moreover, that the thoughts of the epistle are admirable, and not inferior to the acknowledged apostolic writings, anyone who carefully examines the apostolic text will admit.’ 13 Farther on he adds: If I gave my opinion, I should say that the thoughts are those of the apostle, but the diction and phraseology are those of someone who remembered the apostolic teachings, and wrote down at his leisure what had been said by his teacher. Therefore if any church holds that this epistle is by Paul, let it be commended for this. For not without reason have the ancients handed it down as Paul’s. 14 But who wrote the epistle, in truth, God knows. The statement of some who have gone before us is that Clement, bishop of the Romans, wrote the epistle, and of others that Luke, the author of the Gospel and the Acts, wrote it. But let this suffice on these matters.
D) Irenaeus (AD 130-200)
Eusebius also mentions Irenaeus in relation to the author of Hebrews (5.26), but is not clear regarding what Irenaeus’s beliefs are as to who wrote it.
Ecclesiastical History 5.26 Besides the works and letters of Irenæus which we have mentioned, a certain book of his On Knowledge, written against the Greeks, very concise and remarkably forcible, is extant; and another, which he dedicated to a brother Marcian, In Demonstration of the Apostolic Preaching; and a volume containing various Dissertations, in which he mentions the Epistle to the Hebrews and the so-called Wisdom of Solomon, making quotations from them. These are the works of Irenæus which have come to our knowledge.
3) Tertullian (c. AD 160/170 – 215/220)
Tertullian states that Barnabas wrote Hebrews, as if it were common knowledge.
On Modesty 20 For there is extant withal an Epistle to the Hebrews under the name of Barnabas — a man sufficiently accredited by God, as being one whom Paul has stationed next to himself in the uninterrupted observance of abstinence: Or else, I alone and Barnabas, have not we the power of working? And, of course, the Epistle of Barnabas is more generally received among the Churches than that apocryphal Shepherd of adulterers.
4) p46 (c. AD 200)
This papyrus document is the oldest extant text of Hebrews. Notably, it follows Romans (due to length) in a 14-letter Pauline collection instead of coming after Philemon; cf. Allen, Hebrews, 31.
5) Augustine (AD 354-430)
F. F. Bruce, The Epistle to the Hebrews, 17, quotes A. Souter, The Text and Canon of the New Testament (1954), 174, who notes that early on Augustine began by citing Hebrews as Pauline, then in the middle period he wavers between Paul and anonymity, then in old age he refers to the epistle as anonymous. I was not able to track down all of Augustine’s references to Hebrews, but here are several helpful ones.
Forgiveness of Sins 1.50 Although the authority of the Epistle to the Hebrews is doubted by some, nevertheless, as I find it sometimes thought by persons, who oppose our opinion touching the baptism of infants, to contain evidence in favour of their own views, we shall notice the pointed testimony it bears in our behalf
On Christian Learning 2.8.13 That of the New Testament, again, is contained within the following:— Four books of the Gospel, according to Matthew, according to Mark, according to Luke, according to John; fourteen epistles of the Apostle Paul— one to the Romans, two to the Corinthians, one to the Galatians, to the Ephesians, to the Philippians, two to the Thessalonians, one to the Colossians, two to Timothy, one to Titus, to Philemon, to the Hebrews: two of Peter; three of John; one of Jude; and one of James; one book of the Acts of the Apostles; and one of the Revelation of John.
6) Jerome (AD 347-420)
Jerome knew many Latins had doubts about Pauline authorship of Hebrews, and he distinguishes it from Paul’s letters. Ultimately, he said it doesn’t really matter who wrote the letter.
Epistle 53.9 The apostle Paul writes to seven churches (for the eighth epistle — that to the Hebrews — is not generally counted in with the others).
Note: Bruce, Hebrews, 17, also notes 129.3, but this appears to be an incorrect citation, and I am unsure what he meant to reference.
Lives of Industrious Men 5 The epistle which is called the Epistle to the Hebrews is not considered his, on account of its difference from the others in style and language, but it is reckoned, either according to Tertullian to be the work of Barnabas, or according to others, to be by Luke the Evangelist or Clement afterwards bishop of the church at Rome, who, they say, arranged and adorned the ideas of Paul in his own language, though to be sure, since Paul was writing to Hebrews and was in disrepute among them he may have omitted his name from the salutation on this account. He being a Hebrew wrote Hebrew, that is his own tongue and most fluently while the things which were eloquently written in Hebrew were more eloquently turned into Greek and this is the reason why it seems to differ from other epistles of Paul.
7) Synods and Councils
The Synod of Hippo (AD 393) and the Third Synod of Carthage (AD 397) both say: “Of Paul the apostle, thirteen epistles; of the same to the Hebrews, one.”
[Bruce, Hebrews, 17]
They also locate Hebrews at the end of the 13 Pauline letters, indicating the uncertainty of Pauline scholarship (Allen, Hebrews, 33).
The Council of Carthage (AD 419) assigned 14 letters to Paul.
See Canon 24. [https://www.newadvent.org/fathers/3816.htm]
8) Other Witnesses
Being a busy pastor, I was not able to track down all the original sources and references that I read through secondary sources in order to confirm their accuracy. Most sources above are original. Here are a few other individuals mentioned in secondary sources that I was not able to verify, but nonetheless likely reflect accurate assessments.
A) Athanasius (c. AD 300s)
Athanasius places Hebrews among the Pauline letters, placing it after the letters addressed to churches and before the letters addressed to individuals. This same placement is also reflected in Codexes Sinaiticus, Alexandrinus, and Vaticanus, all produced in the 4th and 5th centuries (Allen, Hebrews, 33).
B) Hippolytus (AD 170-235)
William Lane, in the first of his excellent two-volume commentary on Hebrews, notes that Hippolytus argues for Pauline authorship (clii). I could not find a reference to Paul or Hebrews where he notes, though.
C) Ambrosiaster (c. AD 370)
Bruce, Hebrews, 16, notes that Ambrosiaster’s commentary on the Pauline epistles does not include Hebrews, though Ambrosiaster does still consider the epistle canonical.