A religious teacher aligned with PAS has apologised to Parti Amanah Negara (Amanah) president Mohamad Sabu for his overzealous remarks.

During a speech on nomination day for the Kuala Kangsar by-election, Abdullah Khairi had referred to Mohamad Sabu as "Mat Sabun (soap)."

Mohamad Sabu is popularly known as Mat Sabu.

In a short video clip posted on Facebook, Abdullah said: "On this blessed Friday in the month of Ramadan, I wish to apologise to Mohamad Sabu for my emotional speech."

"Abang Mohamad, forgive me," he added in a serious tone.

Abdullah’s speech had drawn flak on the social media, with numerous commentators condemning the religious teacher for his remarks.

In the video, Abdullah said those who scolded and insulted him must seek forgiveness from him.

"These people who scolded and insulted me are also not free of sin either. They must ask for my forgiveness," he added.

Mohamad Sabu, a former PAS deputy president, formed Amanah with several other ex-PAS leaders in the wake of opposition coalition Pakatan Rakyat's collapse.

Amanah is often criticised by PAS and Umno for being a DAP stooge.

In the Kuala Kangsar by-election, Amanah's Ahmad Termizi Ramli is embroiled in a four-cornered fight with PAS' Dr Najihatussalehah Ahmad, BN’s Mastura Mohd Yazid and Independent candidate Izat Bukhary Ismail Bukhary.

The seat fell vacant following the death of Mastura's husband and incumbent MP Wan Khair-il Anuar Wan Ahmad in a helicopter crash.

Both the Kuala Kangsar and Sungai Besar by-elections, to be held simultaneously on June 18, are considered an acid test for Amanah, with regard to whether it can garner the support of Malay voters and be considered a potent threat to PAS.