Not much is known about this decapitation as the executioner did not mention the reason of the beheading. He was just reciting this Quranic verse:
Fight them; Allah will punish them by your hands and will disgrace them and give you victory over them and satisfy the breasts of a believing people.
And remove the fury in the believers’ hearts. And Allah turns in forgiveness to whom He wills; and Allah is Knowing and Wise.
The condemned, with his head bent forward, was decapitated with a single chop to the back of his neck. Beheadings are always savage, but this certainly beats slow and agonizing beheadings by dull knife to the neck.
Props to Best Gore member DerSteppenwolf for the video and translation: