Rex Tillerson has called for people to “treat eachother with respect” in an apparent dig at Donald Trump during his farewell speech.
Mr Tillerson, who was fired as US secretary of state via tweet, also dubbed Washington a “very mean-spirited town” in coded rebuke of the president.
That second statement drew laughter from the crowd of diplomats who appeared to connect the comment to Mr Trump’s treatment of Mr Tillerson.
The remarks were made as Mr Tillerson approaches the end of his troubled tenure as America’s top diplomat, which lasted little more than a year.
Mr Tillerson repeatedly clashed with the president who appointed him over North Korea and the Iran nuclear deal, often being rebuked via tweet by Mr Trump.
He was dismissed earlier this month without receiving a phone call from the president himself, according to State Department officials.
John Kelly, the White House chief of staff, even reportedly revealed that Mr Tillerson had been informed when he was in the toilet.
Addressing diplomats before he leaves at the end of the month, Mr Tillerson appeared to hint at Mr Trump’s behaviour - though did not mention the president by name.
He said: “Finally, I hope you will continue to treat each other with respect. Regardless of the job title, the station in life or your role, everyone is important to the State Department. We’re all just human beings trying to do our part.
“In closing, I would like to ask that each of you undertake to ensure one act of kindness each day towards another person.
“This can be a very mean-spirited town, but you don’t have to choose to participate in that. Each of us gets to choose the person we want to be and the way we want to be treated and the way we will treat others.”
Mr Tillerson has largely kept quiet on his battles with Mr Trump since taking office, playing down tensions in media interviews and public appearances.
He was said to have riled the president by refusing to deny he once called him a "f****** moron” in private.
Mr Tillerson will be replaced by Mike Pompeo, the CIA director, as secretary of state, pending confirmation by the US Senate.
The former ExxonMobil executive will not take up another position in the Trump administration but has said he will return his life as a private citizen.
More News on Rex Tillerson: