Athanasius and Canon of Old Testament

Athanasius (c. 300 to 373 AD) was bishop of Alexandria from 328 to 373 AD.  He was known as one of strong opponent of Arianism. His festal letters were his homilies where in one of them he gave list of Old and New Testament books.  His list of New Testament books is the earliest list with twenty-seven books as we have now (English translation from The Nicene and Post-Nicene Fathers, Series II, Vol. 14, Vol. 4):

There are, then, of the Old Testament, twenty-two books in number; for, as I have heard, it is handed down that this is the number of the letters among the Hebrews; their respective order and names being as follows. The first is Genesis, then Exodus, next Leviticus, after that Numbers, and then Deuteronomy. Following these there is Joshua, the son of Nun, then Judges, then Ruth. And again, after these four books of Kings, the first and second being reckoned as one book, and so likewise the third and fourth as one book. And again, the first and second of the Chronicles are reckoned as one book. Again Ezra, the first and second are similarly one book. After these there is the book of Psalms, then the Proverbs, next Ecclesiastes, and the Song of Songs. Job follows, then the Prophets, the twelve being reckoned as one book. Then Isaiah, one book, then Jeremiah with Baruch, Lamentations, and the epistle, one book; afterwards, Ezekiel and Daniel, each one book. Thus far constitutes the Old Testament. 

But for greater exactness I add this also, writing of necessity; that there are other books besides these not indeed included in the Canon, but appointed by the Fathers to be read by those who newly join us, and who wish for instruction in the word of godliness. The Wisdom of Solomon, and the Wisdom of Sirach, and Esther, and Judith, and Tobit

Athanasius, 39th Festal Letter

His list has twenty-two books corresponding to twenty-two letters of Hebrew alphabet.  They comprise five books of Moses, Joshua, Judges, Ruth, four books of Kings (Samuel and Kings) counted as two books, Chronicles, Ezra 1 and 2 (Nehemiah) in one book, Psalms, Proverbs, Ecclesiastes, Song of Songs, Job and ends with books of Prophets (Twelve minor prophets, Isaiah, Jeremiah, Ezekiel and Daniel).  Athanasius list has Baruch and Letter of Jeremiah as part of Jeremiah together with Lamentations but it omits Esther.  He considered Esther together with Wisdom of Solomon, Sirach, Judith and Tobit as having inferior grade but still approved them to be read (edifying) in the church.  However in his other works, Athanasius cited Tobit, Sirach and Wisdom as scripture, indicating that he did not always restrict himself to only those 22 books (English translation is from The Nicene and Post-Nicene Fathers, Series II, Vol. 4 with added scripture reference).

And they are not ashamed to parade the sacred mysteries before Catechumens, and worse than that, even before heathens: whereas, they ought to attend to what is written, `It is good to keep close the secret of a king [Tobit 12:7];’ and as the Lord has charged us, `Give not that which is holy unto the dogs, neither cast ye your pearls before swine [Matthew 7:6].’

Athanasius, Defence Against the Arians 11

Wherefore when Diogenes came, and Syrianus laid in wait for us, both he and we and the people demanded to see the Emperor’s letters, supposing that, as it is written, `Let not a falsehood be spoken before the king [Sirach 7:5];’ so when a king has made a promise, he will not lie, nor change.

Athanasius, History of Arians 52

I congratulate the most excellent Sarapion, that he is striving so earnestly to adorn himself with holy habits, and is thus advancing to higher praise the memory of his father. For, as the Holy Scripture somewhere says, `though his father die, yet he is as though he were not dead: for he has left behind him a memorial of his life [Sirach 30:4].

Athanasius, Defence Against the Arians 66

Since, however, after all his severe sufferings, after his retirement into Gaul, after his sojourn in a foreign and far distant country in the place of his own, after his narrow escape from death through their calumnies, but thanks to the clemency of the Emperor,-distress which would have satisfied even the most cruel enemy,-they are still insensible to shame, are again acting insolently against the Church and Athanasius; and from indignation at his deliverance venture on still more atrocious schemes against him, and are ready with an accusation, fearless of the words in holy Scripture, `A false witness shall not be unpunished [Proverbs 19:5];’ and, `The mouth that belieth slayeth the soul [Wisdom 1:11];’ we therefore are unable longer to hold our peace, being amazed at their wickedness and at the insatiable love of contention displayed in their intrigues.

Athanasius, Defence Against the Arians 3