RNA - "I was deeply hurt ... by the contempt and insult against my religious sect by my colleague, Hamdan al-Azemi," AFP quoted Faisal al-Duwaisan as writing in his resignation letter.
During a debate Tuesday, Azemi "told me: 'you should rectify your sect,'" Duwaisan said.
That triggered a confrontation between Azemi and several Shiite MPs.
At the end of the session, Shiite MP Abdullah al-Tameemi and Azemi briefly quarreled before they were restrained by other lawmakers.
Duwaisan said he will not withdraw his resignation unless Azemi publicly apologies or parliament takes disciplinary action against him.
There are seven Shiite MPs in the 50-member house.
Kuwait issued the national unity law in 2013 amid rising sectarian tension in the oil-rich emirate, where Shiites form around a third of the 1.3 million native population.
The legislation prescribes several years in jail for religious or ethnic hatred.
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