George Mueller, a great man of prayer

Today I listened to Pastor Edmund Chan’s sermon from the Sermon on the Mount series.
The topic: Dealing With Retaliation. Scripture: Matthew 5:38-42 (NASB)

Pastor closed with a quotation from George Mueller.
He said the day George Mueller discovered himself was the day he died to self.

In surfing the net to know more about George Mueller. I came cross the same quotation in
http://realheroes.net/reformers/George_Mueller.html

His quote:
There was a day when I died, utterly died: died to George Mueller, his opinions, preferences, tastes and will; died to the world, its approval or censure; died to the approval or blame even of my brethren and friends. And since then, I have studied only to show myself 'approved unto God.’

The link give valuable inputs on prayer.