John Chrysostom

"For ye have need of patience," not of any addition to your labors, that ye may continue in the same state, that ye may not cast away what has been put into your hands. Ye need nothing else, but so to stand as ye have stood, that when ye come to the end, ye may receive the promise. "For" (he says) "ye have need of patience, that after ye have done the will of God, ye might receive the promise." Ye have need of one thing only, to bear with the delay; not that ye should fight again. …

Homily on Hebrews 21 ↗

Theophylact of Ohrid

You need nothing else besides patience alone: you have everything else, and you need add nothing further. The will of God is that we endure to the end. For, He says, "he who endures to the end shall be saved" (Matt. 10:22). The Apostle persuades them of this in the same way as if someone, seeing that a fighter, having defeated all his opponents, then, not waiting for those who are slow with the victory prizes, wants to leave, unable to bear the thirst and heat, says to him: having accomplished everything, wait a little and you will …

Commentary on Hebrews ↗

Oecumenius

"For you have need of endurance." I seek not increase, but patience, so that you may persevere in the same things. "so that after you have done the will of God."The will of God is that you persevere in the same things until the end, and endure the delay of retribution and promise.

The Pseudo-Oecumenian Catena on Hebrews ↗

Thomas Aquinas

543. – The way to keep it is patience; hence, he says, for you have need of patience. For just as meekness moderates anger, so patience puts a limit to sadness, so that it will not exceed the bounds of reason. But sadness is sometimes caused by evils inflicted or by good deferred: 'Hope that is deferred, afflicts the soul' (Pr. 13:12). But it is properly called patience, when it is concerned with the first; but long-suffering, when it is concerned with the second. …

Commentary on Hebrews ↗