Paula (R) and Ed Kassig share a light moment as happy words of her son Abdul-Rahman Kassig are read during a prayer service honoring his humanitarian work in Syria at the Islamic Society of North America mosque in Plainfield, Indiana October 10, 2014. Kassig, a humanitarian worker held hostage by Islamic State militants, was threatened in a video issued last week by the militants that purported to show the beheading of British aid worker Alan Henning. REUTERS/Chris Bergin (UNITED STATES - Tags: SOCIETY RELIGION CONFLICT POLITICS)