From what Shakespeare play or sonnet is this quotation? "My crown is in my heart, not on my head; Not decked with diamonds & Indian stones,..."

Shakespeare's quote, "My crown is in my heart, not on my head; Not decked with diamonds and Indian stones, Nor to be seen: my crown is called content: A crown it is that seldom kings enjoy" is a powerful one.  It indicates much in terms of the wealth of kings and the spiritual wealth of men, a theme seen in King Lear, amongst other Shakespearean works.  Of particular note in the quote is the contrast between Indian jewels and that of contentment.  Also, note the difference between physical wealth and spiritual gain.  The quote is located in King Henry VI, Part III, act III, scene I.  It is spoken by King Henry VI to the second keeper towards the end of the act.