"And he did not recognize him, because his hands were hairy like the hands of Esau his brother" (Genesis 27:23). When wicked men were to arise from him [from Jacob's line], he did not recognize him. "And he said: Come near, I pray, and kiss me, my son" (Genesis 27:25-26) - you will kiss me at my burial, and no other will kiss me at my burial.
Isaac Did Not Know His Son and the Kiss at the Grave
Yalkut Shimoni on Torah 115:10
(בראשית כז כג) וְלֹא הִכִּירוֹ כִּי הָיוּ יָדָיו כִּידֵי עֵשָׂו אָחִיו, בְּשָׁעָה שֶׁהָיוּ רְשָׁעִים עוֹמְדִים מִמֶּנוּ לֹא הָיָה מַכִּירוֹ. (בראשית כז כה-כו) וַיֹּאמֶר גְּשָׁה נָּא וּשֲׁקָה לִּי בְּנִי, אַתְּ נוֹשְׁקֵנִי בַּקְּבוּרָה וְאֵין אַחֵר נוֹשְׁקֵנִי בַּקְּבוּרָה.