Charles Ellicott Commentary Genesis 27:13

"And his mother said unto him, Upon me be thy curse, my son. Only obey my voice, and go fetch me them." — Genesis 27:13 (ASV)

Upon me be thy curse. —No curse followed upon their conduct; but, on the contrary, Isaac acknowledged the substantial justice of the act of Rebekah and her son, and confirmed Jacob in the possession of the blessing (Genesis 27:33). It seems strange, nevertheless, that neither of them had any scruples at the immorality of the deed, but apparently thought that as the end was right they were justified in using falsehood and treachery.