Ambrose of Milan

I have preserved for you, my brother, the new and the old; that is to say, I hold on to all the commandments of the new and the old Testament. Only the Church can say this: no other congregation says it, nor does the Synagogue, nor does it hold on to the new according to the literal meaning; nor does it hold on to the old according to the spirit. The heresy of Manichaeus does not say it, 'I have preserved for you the Old,' which does not accept the prophets. It is rightly called white, which shines with the grace of both Testaments.

Commentary on the Song of Songs 7.21 ↗

Bede

Let us rise early and go to the vineyards, etc. Thus let us dwell in the villages so that we may rise to cultivate the vineyards; thus let us make our residence among those who have already converted to the faith, and let us also strive to acquire others whom we may dwell among through evangelizing. And rightly she who is to say, Let us rise to the vineyards, has prefaced it with, Early; for Early speaks of the very rising of the true light, through which the world has been rescued from the power of darkness. …

Commentary on the Song of Songs ↗

Robert of Tombelaine

He rises early to the vineyards, because after His resurrection, sitting in the glory of the Father, He also defends the churches He has built. He looks to see whether the vineyard has blossomed, because He weighs every advance of the Church with strict examination. He sees whether the blossoms are bringing forth fruit, because He discerns to what degree of progress the tender and imperfect ones are growing. …

Commentary on the Song of Songs, Chapter 7 ↗