Pochopil jsem to tak, že chceš do proměnné uložit obsah echa. Pak takhle :

$promenna= <<<RETEZ

      <div id='content'> 
       <div id='sample'>
        <div id='mArea1' style='width: 680px; height: 300px; border: 100px solid #000;'>
		     <br><br/>hgfdhgfdh 
	</div>	 
       </div>  

       <script> 
       var area1, area2;
       function toggleArea1() 
       {
      	if(!area1) 
         {
		     area1 = new nicEditor({fullPanel : true}).panelInstance('mArea1',{hasPanel : true});
	       } 
         else 
          {
		       area1.removeInstance('mArea1');
		       area1 = null;
	        }
       }
      
          
       bkLib.onDomLoaded(function() { toggleArea1(); }); 
     
       
       </script>
        ;
RETEZ
 ;