TEMPO.CO, Jakarta- Philippine president Rodrigo Duterte, who once called the pope a "son of a bitch" and told Barack Obama to "go to hell," said that he has promised to God he will not spew expletives again, according to the Associated Press report.

President Duterte had managed to turn heads with his profanities, especially when threatening to kill drug dealers as part of his war on illegal drugs that has left thousands dead since he took office at the end of June 2016.

Duterte made the stunning pledge on arrival in his southern hometown of Davao city late Thursday, October 28, 2016, from a trip to Japan.

While flying home, he said he was looking at the sky while everyone was sound asleep, some snoring, and he heard a voice that said "'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,'" Duterte said.

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

Duterte's vow was met with applause, but he cautioned: "Don't clap too much or else this may get derailed."

He shocked the dominant Roman Catholics last year when he fired an expletive while expressing his disgust over a monstrous traffic jam that trapped him while Pope Francis was visiting Manila. "I wanted to call. 'Pope, you son of a bitch, go home.' Don't visit here anymore," he told a mob of supporters, some of whom laughed.

He later apologized after Filipino bishops expressed shock and outrage.

It's not certain if the 71-year-old president, who has been compared to US Republican presidential candidate Donald Trump because of his brash language, can keep his promise. Duterte has made a similar pledge in June when it became evident that he had won the May 9 presidential elections overwhelmingly on a pledge to end crimes, especially illegal drugs, and corruption.

He said then that he was enjoying his last moments as a "rude person" because "when I become president, when I take my oath of office ... that will be a different story. There will be a metamorphosis."

It did not take long for Duterte to break the promise when he repeatedly leveled SOB-laced tirades against Obama, UN Secretary-General Ban Ki-moon, a few outspoken opposition politicians and human rights advocates, while heaping praises on Chinese and Russian leaders.

AP