Written in Latin. The Cathach is the oldest extant Irish manuscript of the Psalter and the earliest example of Irish writing. It contains a Vulgate version of Psalms XXX (10) to CV (13) with an interpretative rubric or heading before each psalm. It is traditionally ascribed to St. Columba as the copy, made at night in haste by a miraculous light, of a Psalter lent to Columba by St. Finnian. A dispute arose about the ownership of the copy and King Diarmait Mac Cerbhaill gave the judgement “To every cow belongs her calf, therefore to every book belongs its copy”. The arbitration failed and the Psalter of St. Columba passed into the hands of the O’Donnells after the battle of Cul Dremhne in A.D. 561. St. Columba went to Iona in A.D. 563. It is possible to date the manuscript to the late 6th or early 7th century from the script, but modern historical scholarship has cast doubts on the authorship by St. Columba as well as on the dating.
 
Bron: ria.ie.

Troparion – Tone 4
 
First-enthroned of the apostles,
teachers of the universe:
Entreat the Master of all
to grant peace to the world
and to our souls great mercy!

Kontakion – Tone 2
 
O Lord, You have taken up to eternal rest
and to the enjoyment of Your blessings
the two divinely-inspired preachers, the leaders of the Apostles,
for You have accepted their labors and deaths as a sweet-smelling sacrifice,
for You alone know what lies in the hearts of men.
 
Kontakion – Tone 2
 
Today Christ the Rock glorifies with highest honor
The rock of Faith and leader of the Apostles,
Together with Paul and the company of the twelve,
Whose memory we celebrate with eagerness of faith,
Giving glory to the one who gave glory to them!
 
Bron: oca.org