지성이면 감천이다

Etymology
Originally a reformulation according to Korean syntax of the Classical Chinese chengyu, probably ultimately from a line in  (7:12):
 * As for sincerity, it is the way of heaven
 * As for sincerity, it is the way of heaven

Proverb

 * 1) sincerity moves heaven; if one is truly sincere about achieving something, one shall attain it