Isaiah 7:16
15 He will eat sour milk and honey, which will help him know how to reject evil and choose what is right. 16 Here is why this will be so: Before the child knows how to reject evil and choose what is right, the land whose two kings you fear will be desolate. 17 The Lord will bring on you, your people, and your father’s family a time unlike any since Ephraim departed from Judah—the king of Assyria!”
LXX Isaiah 7:16
15 He shall eat butter and honey; before he knows or prefers evil things, he shall choose what is good. 16 For before the child knows good or bad, he defies evil to choose what is good, and the land that you fear from before the two kings will be abandoned. 17 But God will bring on you and on your people and on your ancestral house such days as have not yet come since the day that he took Ephraim away from Ioudas—the king of the Assyrians.”
Notes and References
"... let us look at the translator’s addition of ἀγαθοῦ ἢ κακοῦ in Isaiah 7:16 ... [scholars] have seen a possible link between this and the texts of LXX Deuteronomy 1:39; Numbers 14:23; 32:11. In addition to these texts, de Sousa has also discussed another possible link (1QSa 1:8–11) that was overlooked by his predecessors. He argues (with reference to the latter possible connection) that “there is enough evidence that the choice between ‘good and evil’ is a strong and widespread motif in early Judaism, and it could have made its way into the Isaiah translation and contributed to a reading that deviates from the original.” ...in the LXX the focus is on the child’s unique devotion to τὸ ἀγαθόν; thus showing that the translator’s interest was “in safeguarding the character of the child.” Syntactically, this emphasis on the child’s rejection of evil and choice of ‘the good’ is clearly displayed in the translator’s use of the phrase γνῶναι ἀγαθὸν ἢ κακόν as to offer an “explanation for why the child will select the good without even knowing about evil”. It should be observed that the promise of the desolation of the enemies’ land (in verses 16–17) is found after the announcement of the birth of Immanuel and the understanding of his characteristics ..."
Ngunga, Abi T. Messianism in the Old Greek of Isaiah: An Intertextual Analysis (p. 81) Vandenhoeck & Ruprecht, 2013