Luther: "I am more afraid of my own heart than of the pope and all his cardinals. I have within me the great pope, self"

Over the years, I've received a few messages like this:

I am trying to verify if Luther wrote this quote; "I am more afraid of my own heart than of the pope and all his cardinals. I have within me the great pope,self." I searched the all beggar site plus numerous books and those who quote it never reference where that it can be found. Any ideas where this was said/written?

This appears to be an apocryphal Luther quote with a long history, though I'm not 100% sure. The quote (in its various forms) goes back at least to the 1800's. Here are some examples. The first three examples seem completely different. They are previous to the 1800's. I've included these because parts were eventually tacked on to the quote in question:

They divide us not only from God, but from one another. This I learne, says Luther, from mine owne experience, that I have more cause to feare what is within me, then what is without. (1653)

I more fear what is within me, says Luther, then what comes from without: the storms and winds without do never move the earth, it is only vapours within that causeth earthquakes, (1655)

Luther hit it when he said, I more fear what is within me, than what comes from without; the storms and winds without do never move the earth, it is only vapours within that causeth earthquakes, as philosophers observe. (1762)

The NATURAL HEART- Our Hearts are born enemies to Christ. So sensible was Luther of this, that he said, "I dread my own heart more than the pope and all his cardinals." (1850)

Our hearts are born enemies to Christ. So sensible was Luther of this, that he said, "I dread my own heart more than the pope and all his cardinals." (1851)

Luther used to say, "I am more afraid of my own heart than of the pope and all his cardinals. I have within me the great pope, Self." (1860)

2834. HEART, fear of the. I am more afraid of  my own heart," says Luther, "than of the Pope and all his Cardinals. I have within me the great Pope - Self. (1870)

Martin Luther's great foe was himself. "I am more afraid of my own heart," he said, " than of the pope and all his cardinals. (1875)

"I AM more afraid of my own head," said Luther, "than of the Pope and all his cardinals. I have within me the great "pope, self." (1877)

It is well if one can say with Luther, "I am more afraid of  my own heart," says Luther, "than of the Pope and all his Cardinals. I have within me the great Pope - Self." (1884)

I dread my own heart more than the pope and all his cardinals, for within me is the greater pope, even self. (1994)

“I am more afraid of my own heart than of the Pope and all his cardinals. I have within me the great Pope: Self. I more fear what is within me than anything that might come from without.” (unknown date)

Some other versions link the quote to Luther's famous speech at Worms in 1521:

On the subject of conscience Martin Luther declared before the court of the Roman Empire at Worms in 1521: "My conscience is captive to the Word of God... I am more afraid of my own heart than of the pope and all his cardinals. I have within me the great pope, "self." [1986]

Just before Luther's audience with the pope, the prelates, the cardinals, and the emperor , a friend moved alongside the maverick monk and asked, "Brother Martin, are you afraid?" Luther responded with a marvelous answer:  Greater than the pope and all his cardinals, I fear most that great pope, self."(1995)

On a later occasion, while awaiting an audience before the prelates of the church, Luther was asked if he were now afraid. "Afraid? Greater than the pope and all his cardinals, I fear most that great pope, self." (2008)

The last two quotes come from Chuck Swindoll. He documents the quote to Revivals Their Laws and Leaders by James Burns, p. 167-168. These pages do not contain the quote, but rather a description of Luther at Worms, 1521. A typical example of Luther's full speech can be found here (and here), and it doesn't appear to me that this quote comes from this speech. By looking through the various versions of the quote, it appears that it was tacked on to Luther's speech at Worms.

A real Luther quote? I'm tempted to say no, at least not in the form it's usually presented in. It could be a truncated synopsis of a much larger writing. That is, someone may have summarized a section with the quote serving as a summary statement.