14 The Letter to the Hebrews explains the difference between the brothers as one of faith—Abel by faith offered a better sacrifice. Cain’s offering as well as his reaction to God’s displeasure did not reflect faith. See further B. K. Waltke, “Cain and His Offering,” 48 (1986): .
15 Heb “and it was hot to Cain.” This Hebrew idiom means that Cain “burned” with anger.
16 Heb “And his face fell.” The idiom means that the inner anger is reflected in Cain’s facial expression. The fallen or downcast face expresses anger, dejection, or depression. Conversely, in Num 6 the high priestly blessing speaks of the Lord lifting up his face and giving peace.

In other versions

but for Cain and his offering he had no regard. So Cain was very angry, and his face fell.

but on Cain and his offering he did not look with favor. So Cain was very angry, and his face was downcast.

but he did not have regard for Cain and his offering. Cain was furious, and he looked despondent.

but he did not accept Cain and his gift. This made Cain very angry, and he looked dejected.

but to Cain and to his offering he did not look with favor. And Cain became very angry, and his face fell.

But unto Cain and to his offering he had not respect. And Cain was very wroth, and his countenance fell.

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