John Chrysostom

For the assertion, "Seeing that it was not possible that He should be holden of it," means this, that His rising was not common to the rest. Then, however, before their thoughts can enter at all into his meaning, he brings David upon them, an authority which sets aside all human reasoning. "For David saith (with reference) to Him." And observe how, once more, the testimony is lowly. …

Homily on Acts 6 ↗

Theophylact of Ohrid

Next he brings forward David, who surpasses all human reason, because this kind of thing is prophecy, and says: "For David says concerning Him," and not concerning himself; and again he begins from the side of humility. Although this has been accomplished now, it was foreordained from of old: God consented to this from the beginning and foreordained it from the beginning. "I saw the Lord before me always." He calls the Father the Lord of Jesus, because Jesus took on the form of a servant. …

Commentary on Acts ↗

Bede

For David says in reference to Him, that is, in His person: I foresaw the Lord always before me, because He is at my right hand, that I may not be moved. By explaining what the Mediator of God and men did, He gives us who are pure men advice on how to avoid sins. For whoever continuously looks upon the presence of his Creator with the eye of his mind in no way turns to sins. He also states the reason why he was not moved. …

Retractions on Acts ↗