The giving and taking of offence is a shock jock's stock-in-trade. But the offence is not usually of the criminal variety.

Questions are now being raised about whether Sydney radio host Ray Hadley may have broken the law by exhorting the now-treasurer Scott Morrison to swear on the Bible during a bruising post-coup encounter last Friday.

Hadley assured Mr Morrison the Bible was "always there" in the 2GB Canberra studio, and it would "be easier for people to believe you" if he'd swear an oath about where his political allegiances lay.

"It's not a stunt," Hadley insisted as Mr Morrison expressed his indignation at the prospect of his faith being "used as a stunt". "It's a way of proving people are telling the truth."