The reading is from St. Paul's Letter to the Hebrews 12:1-10

BRETHREN, since we are surrounded by so great a cloud of witnesses, let us also lay aside every weight, and sin which clings so closely, and let us run with perseverance the race that is set before us, looking to Jesus the pioneer and perfecter of our faith, who for the joy that was set before him endured the cross, despising the shame, and is seated at the right hand of the throne of God. Consider him who endured from sinners such hostility against himself, so that you may not grow weary or fainthearted. In your struggle against sin you have not yet resisted to the point of shedding your blood. And have you forgotten the exhortation which addresses you as sons? "My son, do not regard lightly the discipline of the Lord, nor lose courage when you are punished by him. For the Lord disciplines him whom he loves, and chastises every son whom he receives." It is for discipline that you have to endure. God is treating you as sons; for what son is there whom his father does not discipline? If you are left without discipline, in which all have participated, then you are illegitimate children and not sons. Besides this, we have had earthly fathers to discipline us and we respected them. Shall we not much more be subject to the Father.