只要功夫深，铁杵磨成针 [zhǐ yào gōng fu shēn tiě chǔ mó chéng zhēn]

Constant grinding can turn an iron rod into a needle; Constant dropping wears away a stone; if you work at it hard enough you can grind an iron rod into a needle -- perseverance spells success; Little strokes fell great oaks; With time and patience the leaf of the mulberry becomes satin;