Athanasius of Alexandria

Knowing once more how the will of man could sway to either side, in anticipation God secured the grace given them by a command and by the place where he put them. For he brought them into his own garden and gave them a law so that, if they kept the grace and remained good, they might still keep the life in paradise without sorrow or pain or care, besides having the promise of incorruption in heaven. …

On the Incarnation of the Word 3.4 ↗

Cyril of Jerusalem

Although to Adam it was said "For the day you eat of it, you must die," today you have been faithful. Today will bring you salvation. The tree brought ruin to Adam; the tree [of life] shall bring you into paradise. Fear not the serpent; he shall not cast you out, for he has fallen from heaven. I say not to you, "This day you shall depart," but "This day you shall be with me."

Catechetical Lecture 13:31 ↗

Ambrose of Milan

Why did He use the singular 'thou shalt eat' when He bade them eat of every tree, and, again, when He bade them eat of the tree of good and evil, why did He use the plural 'You shall not eat'? This is no trifling question. This problem can, in fact, be solved by the authority of the Scriptures if you study them carefully. Scripture refers to something good and something that should be done. What is good is naturally associated with what should be done. On the other hand, what is base is separate and unrelated to what should be done. …

On Paradise ↗

Bede

And He commanded him, saying: Of every tree of the garden you may freely eat, but of the tree of the knowledge of good and evil you shall not eat. It is not to be believed that there was anything naturally evil in that tree, as we have also taught above, but man was forbidden from that which was not evil, so that the very observance of the command itself would be good for him and its transgression evil. …

Commentary on Genesis (Hexaemeron) ↗