St Luke, Evangelist
To me, Thy friends, O God, are made exceedingly honourable; their principality is exceedingly strengthened. * Lord, Thou hast proved me and known me: Thou hast known my sitting down and my rising up.
(Psalm 138:17,1-2, from the Introit of Mass).
Interveniat pro nobis, quaesumus, Domine, sanctus tuus Lucas Evangelista: qui crucis mortificationem iugiter in suo corpore, pro tui nominis honore, portavit.
We beseech Thee, O Lord, grant us to be aided by the prayers of Saint Luke thine Evangelist; who for the glory of Thy name ever bore in his body the mortification of the cross.
Catholic encyclopaedia on St Luke and his gospel: http://www.newadvent.org/cathen/09420a.htm