For missing Friday prayers at central mosque, a 14-year-old boy was beheaded by an Islamic State (ISIS) executioner before a large crowd that included his parents in Jarbalus, northern Syria last Saturday, according to reports.

ARA News reported that the teenager was initially arrested and then sentenced to beheading for "apostasy'' or abandoning Islam.

Civil rights activist Nasser Taljbini told the paper that "dozens of people attended the brutal execution, including the victim's parents who were forced to witness the beheading of their own son.''

"ISIS is trying to prove that it is still powerful despite all the military defeats. The group is trying to terrorise people through conducting such public punishments,'' Taljbini said.

The execution took place near the Turkish-Syria border in a strategic stronghold for ISIS where foreign jihadis are smuggled into Syria.

Earlier, Kurdish forces bombarded Jarbalus with artillery shells and mortar fire, killing several ISIS fighters, reports said.

In another report, the terror group's affiliate in Yemen also executed men and women in a market and beheaded four prisoners.

The horrific violence was shown in a 21-minute long propaganda video reportedly filmed in Hadramaut, western Yemen and was filmed from the point of view of the gunmen. It was released Feb. 3 and posted in different pro-ISIS accounts.

"ISIS affiliates in Yemen have beheaded four prisoners before opening fire in a busy market killing at least two men,'' the Daily Mail reported.

The four men were labelled ''soldiers of the apostate'' and forced to kneel as they were beheaded by masked knifemen, while the two men were shot in a market for being ''murtad'' by rejecting Islam, the report said.

ISIS affiliates in Yemen also reportedly attacked a village and blew up buildings after capturing weapons.

The video also shows the militants planning attacks before making a night assault on what has been reported as a Houthi or Al-Qaeda outpost. It likewise features recruits holding training and doing press ups and sit ups as well as fighting exercises with a knife with their instructor counting their repetitions in Arabic, according to reports.

Yemen has been torn apart by civil war as Iranian-back Houthis fight the Saudi-backed government.