Catena Fidei

Genesis 4:5 (WEB)
but he didn’t respect Cain and his offering. Cain was very angry, and the expression on his face fell.

Catechism · 2

§2538Article 10 · The Tenth CommandmentRead at vatican.va
“Envy can lead to the worst crimes.” — Catechism footnote: Cf. Gen 4:3-7; 1 Kings 21:1-29.

§401Paragraph 7 · The FallRead at vatican.va
“Likewise, sin frequently manifests itself in the history of Israel, especially as infidelity to the God of the Covenant and as transgression of the Law of Moses. and even after Christ's atonement, sin raises its head in countless ways among Christians.” — Catechism footnote: Cf. Gen 4:3-15; 6:5, 12; Rom 1:18-32; I Cor 1-6; Rev 2-3.

Tertullian, An Answer to the Jews Chapter 2
“…He accepted what he was offering in simplicity of heart, and reprobated the sacrifice of his brother Cain, who was not rightly dividing what he was offering.” — editor's note: Gen. iv. 1–7, especially in the LXX.; comp. Heb. xi. 4.
Read the whole comment
Tertullian, An Answer to the Jews Chapter 5
“Groaning and trembling shalt thou be upon the earth, and every one who shall have found thee shall slay thee.”” — editor's note: See Gen. iv. 2–14. But it is to be observed that the version given in our author differs widely in some particulars from the Heb. and the LXX.
Read the whole comment

Gregory the Great, Epistles, Books IX–XIV IX.57Book IX
“For hence it is that it is written, The Lord had respect unto Abel and to his gifts, but unto Cain and to his gifts he had not respect (Gen. iv. 4, 5).” — the author cites it
Read the whole comment

Hippolytus of Rome, The Refutation of All Heresies V.11Book V
“This, he says, is Cain, whose sacrifice the god of this world did not accept.” — editor's note: Gen. iv. 5.
Read the whole comment