The collect for today, the Feast of Saint Luke the Evangelist, from the 1662 Book of Common Prayer:

Almighty God, who calledst Luke the Physician, whose praise is in the Gospel, to be an Evangelist, and Physician of the soul; May it please thee, that, by the wholesome medicines of the doctrine delivered by him, all the diseases of our souls may be healed; through the merits of thy Son Jesus Christ our Lord. Amen.

The Epistle: 2 Timothy 4:5-15
The Gospel: St Luke 10:1-7a

 More on St Luke here.