勤火叱

Adverb

 * 1) diligently

Reconstruction notes
The pronunciation is unknown due to a lack of Middle Korean reflex. The final syllable is reconstructed as. While Hwang et al. 2009 classifies this as an adverb with phonogramic final-syllable marking, there is an opposing argument that is simply the homophonous emphatic particle  applied to an adverb.