Isaiah 53:5
"But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed."
This messianic prophecy — fulfilled in Christ's crucifixion — speaks primarily of spiritual healing through the atonement. Matthew 8:17 applies it to physical healing as well, showing healing is woven into the meaning of the cross.