刀不磨要生锈，人不学要落后

dāo bù mó yào shēng xiù , rén bù xué yào luò hòudaobumoyaoshengxiu,renbuxueyaoluohou

1. (proverb) a blade will get rusty if it is not sharpened; a man will fall behind if he doesn't study

Study it in Yanamino