Genesis 4:4
3 At the designated time Cain brought some of the fruit of the ground for an offering to the Lord. 4 But Abel brought some of the firstborn of his flock—even the fattest of them. And the Lord was pleased with Abel and his offering, 5 but with Cain and his offering he was not pleased. So Cain became very angry, and his expression was downcast.
LXX Genesis 4:4
3 And it came about after some days that Kain brought to the Lord an offering of the fruits of the earth, 4 and Habel, he also brought of the firstlings of his sheep and of their fat portions. And God looked upon Habel and upon his gifts, 5 but on Kain and on his offerings he was not intent. And it distressed Kain exceedingly, and he collapsed in countenance.
Notes and References
"... Arbitrariness in God... Already in the Septuagint of Genesis, we find alterations of this kind. If it is not possible to accuse God of wickedness, the responsibility must fall on a human being. The case of Genesis 4:4 is well-known. According to the Hebrew text, both Cain and Abel offer a החנמ ("gift"). In the Septuagint, we find a distinction: Cain’s offering is called a θυσία ("sacrifice"), whereas Abel’s offering is designated a δῶρον ("gift"). Based on this differentiation, later readers of Genesis 4 emphasized the higher value of Abel’s offering, which signifies a higher degree of piety ..."
Meiser, Martin The Septuagint and Its Reception: Collected Essays (p. 21) Mohr Siebeck, 2022