From Chapter XVII. of the Book St. Basil Wrote to Blessed Amphilochius on the Holy Ghost.
(Found translated in lib. cit., p. 40 et seqq.)
He speaks of the written doctrine, and the unwritten tradition of the Apostles, and says, that both have the same efficacy as to religion. The unwritten traditions which he mentions, are the signing those who hope in Christ with the Cross; praying toward the East, to denote, that we are in quest of Eden, that garden in the East from whence our first parents were ejected (as he afterwards explains it), the words of invocation at the consecration of the Bread of Eucharist, and the cup of eulogy; the benediction of the baptismal water, the chrism and of the baptized person; the trine immersion, and the renunciations made at baptism; all which the Fathers concealed from those who were not initiated. He says the dogmata were always kept secret, the Kerugmata published; he adds the tradition of standing at prayer on the first day of the week, and the whole Pentecost (that is, from Easter to Whitsunday), not only to denote our rising with Christ, but as a prefiguration of our expecting an eternal perfect day, for the enjoyment of which we erect ourselves; and lastly, the profession of our faith in Father, Son and Holy Ghost at baptism.
He asserts the Doxology [in these words] “with the Holy Spirit,” to be an unwritten, Apostolic tradition. For this is a dogma full of authority, venerable for its antiquity.