Former Uruguayan leader José Mujica, who was dubbed "the world's poorest president" for his modest lifestyle, says he does not want any pension from his time as a senator.
Mr Mujica resigned on Tuesday from the post of senator, which he had held since 2015, when his five-year-term as president had ended.
He said he would not serve out his term until 2020 because as he was "tired after a long journey".
The former left-wing rebel is 83.
The ex-president made his resignation official in a letter to the head of the Senate, Lucía Topolansky, who is also Uruguay's vice-president and Mr Mujica's wife of 13 years.
In it he said "the motives [for resigning] are personal, I would call them 'tiredness after a long journey'."
"Nevertheless, while my mind works, I can't resign from solidarity and the battle of ideas," the letter continued.
Mr Mujica, who is known for his direct and sometimes colourful language, also apologised to "any colleagues I may have personally hurt in the heat of the debate".
In 2013, he had to apologise to the then-president of Argentina, Cristina Fernández de Kirchner, after calling her an "old hag" and labelling her husband and former president, Néstor Kirchner, who had a lazy eye, "the cross-eyed man".
His comments had been recorded at a news conference when he did not realise the microphone was on.
In 2016, he said the president of Venezuela, Nicolás Maduro, was "as mad as a goat".
But it was his down-to-earth lifestyle and refusal to live in the presidential palace during his time in office which made him really famous.
Then and now, he and his wife, who was his life partner and fellow guerrilla fighter long before they married in 2005, live on a modest flower farm on the outskirts of Montevideo.
He donated most of his salary as president to charity and the only possession he had when he took office in 2010 was his 1987 Volkswagen Beetle.
The light-blue, beat-up Beetle became so famous he was offered $1m (£780,000) for it in 2014, but turned the offer down because he said he would have no way of transporting his three-legged dog without it.
Mr Mujica's resignation letter did not come as a surprise as he had announced that he would send it during his last appearance in the Senate on 3 August.
During the session, some of his political rivals said that they were not sure whether to believe his assurances that he would retire from active politics for good.
Senator Luis Alberto Heber referred to rumours that Mr Mujica was stepping down to run for president for a second time in 2019.
"We naturally think that it's great that you want to spend your free time resting rather than working against our party and for yours, we wish you a peaceful rest!" he said.
While his colleagues in the Senate wished him well, some of his critics on social media said he should have apologised for his actions during his time as a member of the armed left-wing rebel group Tupamaros in the 1960s and 70s.