Rizal Mansor has challenged Dr Mahathir Mohamad lawyer's Haniff Khatri Abdulla to sue him for defamation.

This is after Haniff accused the aide to Prime Minister Najib Abdul Razak's wife of slander for claiming that Mahathir belittled Prophet Muhammad during the DAP convention over the weekend.

"Where is the slander? It is slander if I fabricated stories that are not true, spreading tales about something Mahathir never said.

"However, Mahathir's lawyer himself admitted that what I said was exactly what Mahathir said (in his speech).

"Sue me if it is slander," Rizal said in a Facebook post today.

Previously, Rizal accused Mahathir of wanting to outshine DAP, and therefore was willing to belittle the prophet.

In retaliation, Haniff had claimed Rizal lacked the intelligence to comprehend Mahathir's remarks, or had deliberately twisted the manner.

He said the former premier merely noted how Prime Minister Najib Abdul Razak purportedly compared himself to Prophet Muhammad.

“But the prophet of Islam as you know did not have 1MDB... He did not have RM2.6 billion in his account, that is why we look up to him ... but Najib, he should be placed in a court of law to answer for all the things that he has done...,” Mahathir had added.

Based on this, Haniff said it is clear Mahathir never insulted the prophet.

However, in his posting today, Rizal argued that leaders who embodied the spirit of Islam would never mock the Prophet Muhammad, especially in the presence of a party filled with non-Muslim leaders and members.

During his speech at the Umno meet last week, Najib said while some advised him to respond in the same harsh manner as his critics, he however preferred to adhere to the teachings of the prophet, who emphasised on being civil even with foes.

Najib has denied abusing public funds for personal gain and accused Mahathir, who insists that the prime minister is embroiled in corruption, of attempting to topple him from power.

Attorney-general Mohamed Apandi Ali has cleared the prime minister of any wrongdoing and the RM2.6 billion is described as a donation from a Saudi royalty.