President Rodrigo Duterte has promised to God and the Filipino people that he would refrain from issuing expletives.

He made the pledge upon his return from a three-day official visit to Japan Thursday night at the Davao International Airport.

"So I promise God not to express slang, cuss words and everything. So, you guys, hear me right always because promise to God is a promise to the Filipino people," Duterte said.

Duterte said while he was on board the plane going back to Davao City from Tokyo and while his companions were sleeping, heard a voice telling him to stop making diatribes.

"I was looking at the skies while I was coming over here...everybody was asleep, snoring, but a voice said that, you know, ‘if you don’t stop epithets, I will bring this plane down now.’ And I said, ‘who is this?’ So, of course, it’s God,"he said.

The audience applauded but Duterte said:"Don't clap too much or else this may get derailed."

Duterte has been known for being foul-mouthed. Even when he was still campaigning, he was criticized for uttering "son of a bitch" against Pope Francis whose presence in Manila caused monstrous traffic jam. Celerina Monte/DMS