The introduction to The Healing.
It begins by saying: prayer has helpers and witnesses... Then it says: Witness to forgiveness and helper in prayer, giver of the certainty that you will finally reach the goal, that is healing. But, immediately afterward, it says that its importance should not be overemphasized, for healing is a sign or symbol of the power of forgiveness...
And I won't continue because it's painful.
Forgiveness is Jesus' forgiveness of what you atone for. When it says... shadow of a change: the change is in your thought system due to the Atonement. And healing is the fruit of the Atonement. You were healed of your illness; therefore, the cause was undone by Jesus, and as a result, your mind has been healed, and the effect, which was the illness, disappears.
You realized that this wasn't dictated by Jesus. If you want to see more content on this, I invite you to watch video number 5 of the section "Correcting A Course in Miracles in Videos."