The Pow (Forward) hitmaker became angry after seeing Fazer post a snap on his Instagram.com page showing a sparkling gun and matching ammunition, alongside the caption, "U (sic) ain't worth my bullets!"
Lethal Bizzle aimed a message at him via Twitter.com, writing, "U ain't bout dat life bruv (sic), posting gun pics? What a wally (fool)."
Fazer hit back by branding his rap rival "childish", prompting Bizzle to respond with, "No one cares how many pop records u (you) sold... I've sold less but guess what? I'm richer & more relevant than u (sic)."
He also mocked Fazer's former N-Dubz bandmate Dappy by referring to his rumoured money troubles, adding, "P.S. lend Dappy a tenner."
Dappy was recently forced to deny rumours suggesting he had filed for bankruptcy.