At the end of his 51 -day "march and fast" initiative for jailed PKR de facto leader Anwar Ibrahim to be freed, disabled activist Isaiah Jacob has issued a warning to Prime Minister Najib Abdul Razak.

Speaking outside the Pasar Seni complex in Kuala Lumpur, the final stop on his journey, Isaiah warned Najib that it will not be the end of the road for his struggle to free Anwar.

"I am warning, or I am setting a condition for Najib, our prime minister, if he is as he says, ‘anak jantan’ (a man).

"I challenge him, if he is really 'jantan', face this OKU...," said the PKR Batu member in his speech, alluding to Najib's swipe at Anwar in his opening speech at the Umno General Assembly on Thursday.

"If he can't free Anwar, we will rise. The people will rise to free Anwar," said Isaiah, who was accompanied by PKR president Dr Wan Azizah Wan Ismail, PKR vice-president Tian Chua, Wangsa Maju MP Tan Kee Kwong, and a number of supporters.

Isaiah also urged the gathered supporters to join the campaign to free Anwar, not just based on their belief in his "innocence," but the need for him to resume leading the federal opposition pact.

"If I as an OKU can rise from among 31 million Malaysians, traveling 2,780km without any fear, fasting for 51 days, I challenge all of you able-bodied persons, for the future of our children, we need to free Anwar," he stressed.

From the entire journey across nine states in the peninsula, Isaiah said he had walked a distance of 472.5km, while only drinking water.

At the various pit stops, he added, there were programmes organised by local PKR leaders and supporters of the Free Anwar campaign.

Asked whether he was afraid of any repercussions from the warning issued to Najib, Isaiah later told reporters that he was only doing the right thing.

"I am not afraid of anybody. I am only afraid of God. We as a human beings, we have to be brave enough, if someone did a mistake, we have to tell them.

"If we do not do it, we do not warn them, we become sinners," he said.

Both Wan Azizah and Tian Chua earlier credited Isaiah for his sacrifice, describing his success as evidence that nothing is impossible to achieve.

Isaiah first announced his "march and fast" initiative on Sept 13, and commenced to walk from Permatang Pauh, Penang – the constituency Anwar held before his sodomy conviction – just over two weeks later.

Earlier this year, several PKR-linked NGOs and supporting groups had petitioned the Yang di-Pertuan Agong Sultan Muhammad V to pardon Anwar in time for the 14th general election.

Anwar is expected to complete his five-year jail term at Sungai Buloh Prison sometime in June next year.

However, he will remain ineligible to run for public office in the coming polls, as the Election Offences Act 1954 bars people who have been convicted within five years prior to the nomination day from participating in the election.