John Gill Commentary Genesis 27:42

"And the words of Esau her elder son were told to Rebekah. And she sent and called Jacob her younger son, and said unto him, Behold, thy brother Esau, as touching thee, doth comfort himself, [purposing] to kill thee." — Genesis 27:42 (ASV)

And these words of Esau her eldest son were told to Rebekah , &c.] Jarchi and Jonathan say, by the Holy Ghost; but Aben Ezra thinks, by one of Esau's friends and confidants, to whom out of the abundance of his heart he had revealed this secret, which is not at all unlikely.

and she sent and called Jacob her younger son ; who might be in another tent or apartment, or with the flocks in the field.

and said to him, behold, your brother Esau, as touching you, does comfort himself, [purposing] to kill you ; he has determined on it, and has laid a scheme for it, and comforts himself with the thought of it, that he shall be able to accomplish it, and so be the heir of the promise, and get the blessing; and even such is his nature, that your death will be a comfort to him under the loss of his blessing, though he gets nothing by it, so sweet is revenge to him.