Rashi on Genesis 22:9/רש"י על בראשית כ״ב:ט׳

1ויעקד AND HE BOUND his hands and feet behind him. Hands and feet tied together is what is meant by עקידה “binding”. It is associated in meaning with עקודים in (Genesis 30:35) “[she-goats] that were streaked” — whose ankles were streaked white so that the place where they are bound could be plainly seen.