* the singers.
  6:31-33  15:16-22  16:4-6  25:1-31  Ezr 7:24 
 * were free.
  Ne 11:17,22,23 
 * they, etc.  Heb. upon them.  employed.
   A number of Levites were employed by rotation in singing the
   praises of Jehovah; and they seem to have continued the
   service day and night:  see the References.

  Ps 134:1,2  135:1-3