Catena Aurea

GREGORY. They then who have neglected till extreme old age to live unto God, have stood idle to the eleventh hour, yet even these the master of the household calls, and oftentimes gives them their reward before other, inasmuch as they depart out of the body into the kingdom before those that seemed to be called in their childhood.

ORIGEN. But this, Why stand ye here all the day idle? is not said to such as having begun in the spirit (Gal. 3:3) have been made perfect by the flesh, as inviting them to return again, and to live in the Spirit. This we speak not to dissuade prodigal sons, who have consumed their substance of evangelic doctrine in riotous living, from returning to their father’s house; but because they are not like those who sinned in their youth, before they had learnt the things of the faith.

CHRYSOSTOM. When He says, The first shall be last, and the last first, He alludes secretly to such as were at the first eminent, and afterwards set at nought virtue; and to others who have been reclaimed from wickedness, and have surpassed many. So that this parable was made to quicken the zeal of those who are converted in extreme old age, that they should not suppose that they shall have less than others.