zhǐ yào gōng fu shēn , tiě chǔ mó chéng zhēn
Translation
- If you work at it hard enough, you can grind an iron bar into a needle.
- cf idiom 磨杵成針|磨杵成针, to grind an iron bar down to a fine needle (idiom)
- fig. to persevere in a difficult task
- to study diligently