Ambrose of Milan

The Church, following this ever-flourishing greenness of grace in Christ, says: "In his shadow I desired, and I sat." The Apostles also received this privilege of the evergreen gift, not a leaf of theirs could ever fall, so that even their shadow could heal the sick. For the weaknesses of the body overshadow the faith of the mind, and the flourishing merits of virtues.

The Six Days of Creation ↗

Bede

"As an apple tree among the trees of the forest, etc." This is what the Psalmist speaks of, "For who in the clouds can be compared to the Lord? Or who is like God among the sons of God?" (Psalm 88). Just as the apple tree, which is pleasing to sight, smell, and taste, tends to surpass the wild trees, so does the man God rightfully surpass all who are pure men among the saints; and the merit of those who are sons of God by grace transcends the power of him who is the son by nature. …

Commentary on the Song of Songs ↗

Bernard of Clairvaux

There follows: "As the apple tree among the trees of the forest, so is my beloved among the sons." The bride returns the exchange of praise to the Bridegroom who commends her, from whom to be praised is to be made praiseworthy, and to praise whom is to understand and admire the praiseworthy one. And just as her praise was figured by the Bridegroom from an eminent flower, so in return she too demonstrates his singular glory and eminence from an excellent tree. …

Sermons on the Song of Songs, Sermon 48 ↗