2006 New York Code - Separate Action For Mortgage Debt.

 
    §  1301.  Separate  action for mortgage debt.  1. Where final judgment
  for the plaintiff has been rendered in an action to recover any part  of
  the  mortgage  debt,  an  action shall not be commenced or maintained to
  foreclose the mortgage, unless an execution against the property of  the
  defendant has been issued upon the judgment to the sheriff of the county
  where  he  resides,  if  he  resides  within the state, or if he resides
  without the state, to the sheriff of the county where the  judgment-roll
  is filed; and has been returned wholly or partly unsatisfied.
    2. The complaint shall state whether any other action has been brought
  to  recover  any part of the mortgage debt, and, if so, whether any part
  has been collected.
    3. While the action  is  pending  or  after  final  judgment  for  the
  plaintiff  therein,  no other action shall be commenced or maintained to
  recover any part of the mortgage debt, without leave  of  the  court  in
  which the former action was brought.