Midrasch zu Mischlej 17:15

"Justifying the wicked and convicting the innocent—Both are an abomination to the Lrd" (Proverbs 17:15) Rabbi Yehoshua son of Levi said ‘it is not because Rivka loved Yaacov more than Esav that she did this thing; but she said that it will not help and confuse that elderly man - for the name of Gd is an abomination to both of them, and because he justified the wicked, his eyes were dim – "it was when Yitzchak was old that his eyes grew dim" Genesis 27:1