餅は餅屋 (もちはもちや): every man knows his own business best; one should go to specialists for the best results; for rice cakes, (go to) the rice cake shop

every man knows his own business best; one should go to specialists for the best results; for rice cakes, (go to) the rice cake shop

For rice cakes, go to the rice cake shop. The polite way to say a job belongs to the person who does it for a living, and it works just as well when that person is you.

A Japanese proverb (ことわざ)