Marking with a dagger stabbing a Magen David.  Historical status as a flag is unknown, possibly dubious, but as a historical emblem or insignia, see images (smaller, larger) linked from  [1]
originally uploaded as File:Arab Liberation Army.svg, version 20:01, 23 April 2011, its source is http://www.ynet.co.il/PicServer2/02022009/2084251/12-Zklarts_043_wh.jpg
Vallecyofdawn, modified by Zscout370