Possible Clues:

• Psalm 51 found on choir stall
• Diocese in predicament about right psalm for Ash Wednesday
• Psalm of mercy
• Is interrupting the speaker about repeated plea for mercy
• Money hoarder, before seeing Psalm 51
• Scrooge, say, before the Mercy Seat
• Piece of religious music from mass is before scripture class
• Psalm 51 which begins 'Have mercy on me, O God'
• Parsimonious person before rendering penitential psalm
• Have mercy, in Latin masses