The High Court in Edinburgh heard that Mudawi, who lived in Portobello, had pulled up in a car accompanied by four others.
CCTV showed him walking purposefully to the promenade where he confronted an 18-year-old.
The teenager then backed away and a 17-year-old stepped in to defend him.
The 17-year-old punched Mudawi who then struck him on the neck with a bladed instrument.
The 18-year-old ran to a property on the neighbouring Mentone Avenue to ask for help.
When he rang the doorbell it activated a camera which captured video and sound of what happened next.
Mudawi arrived and repeatedly stabbed him on the head and neck with a pair of scissors.
Mudawi could be heard saying “this is what thieves get.”