Stick to (one's) knitting spoken language verb phrase
Used to describe minding one's business.
Can you just keep silent and stick to your knitting?
Stick to your knitting. I don't need you to tell me how to do things.
To focus on a certain area one's familiar with.
Don't learn many things at once, just stick to your knitting.
James is sticking to his knitting to become a good doctor.
It's mostly used in the present tense.