pitää kynttiläänsä vakan alla

Etymology
lit. 'to keep one's candle under the bushel', from the Bible.

Verb

 * 1)  to hide one's light under a bushel to conceal one's talents or positive qualities, especially due to modesty or shyness; to avoid attention

Conjugation
See. It also takes a possessive suffix according to the subject of the sentence. is not inflected.