John Chrysostom

"Furthermore, we have had fathers of our flesh which corrected us, and we gave them reverence." Again, he reasons from their own experiences, from what they themselves suffered. For as he says above, "Call to mind the former days," so here also "God" (he saith) "dealeth with you as with sons," and ye could not say, We cannot bear it: yea, "as with sons" tenderly beloved. For if they reverence their "fathers of the flesh," how shall not you reverence your heavenly Father?

Homily on Hebrews 29 ↗

Theophylact of Ohrid

Based on their own circumstances, he again shows that it is necessary to endure. For if, when our fathers according to the flesh disciplined us, we did not dare to withdraw, but, being subjected to shame, patiently bore everything they inflicted upon us, then how much more now, when God disciplines us. Notice, he did not say: let us endure all the more, but: "we should submit," showing that not to endure afflictions is the act of an adversary and enemy of God. …

Commentary on Hebrews ↗

Oecumenius

"and we respected them for it." We heard, he says, and we respected them. "Father of spirits." Whether of spiritual gifts or of souls or spiritual virtues. "and live." For this is life, to be subject to God.

The Pseudo-Oecumenian Catena on Hebrews ↗

Thomas Aquinas

679. – Then (v. 9) he gives the second reason drawn from our own experience, namely, paternal correction. This proceeds according to the twofold difference between God the Father and the father of our flesh. The first difference is that a man begets a man as to the body, but not as to the soul, which is created and not transmitted: 'I have not given you a spirit and a soul' (2 Macc 7:22); hence, he says, We have had earthly fathers to discipline us: 'Have you children? Instruct them' (Sir. 7:25). …

Commentary on Hebrews ↗