Clement of Alexandria

The Scripture makes good sense: "Cain left God's presence and went to live in the land of Nod, opposite Eden." Nod means "disturbance," Eden, "the good life." The good life from which the transgressor was expelled consisted in faith, knowledge, peace. Those wise in their own eyes … are happy to transfer to the disturbance of a tossing sea. They drop from the knowledge of the One who knows no birth to the realm of birth and death. Their opinions are constantly changing.

The Stromata Book 2 ↗

Jerome

And he dwelt in the land of Naid. Which the Septuagint translated as Naid, but in Hebrew it is called Nod, meaning 'shaking', that is, unstable and fluctuating, with an uncertain dwelling place. Therefore, it is not the land of Naid, as our common people think, but the divine sentence is fulfilled, that he wandered and fled here and there.

Hebrew Questions on Genesis ↗

Bede

And Cain went out from the presence of the Lord and dwelt in the land of Nod to the east of Eden. By the presence of the Lord is usually understood the recognition by which He manifests and is known. Therefore, deservedly, the people who have withdrawn from the grace of divine recognition are said to dwell on earth. For they cannot say with the elect, "Our citizenship is in heaven, from where we also eagerly wait for the Savior, the Lord Jesus Christ" (Philippians 3:20). …

Commentary on Genesis (Hexaemeron) ↗