Etymology of '하염없이' - was there ever such a thing as a '하염'?

Question

하염하염없이 is translated by naver dic as **blankly, vacantly**: > 그는 하염없이 벽만 바라보았다 - >He stared blankly at the wall. or **ceaselessly**: > 하염없이 걷다 - > walk endlessly A formation of *X-없이* would normally suggest that X would be a noun with some particular meaning, but there doesn't seem to be such a thing as a '하염'. Was there ever? if not, what's the origin of the word 하염없이?