Let the cobbler stick to his last

Let the cobbler stick to his last.

Prov. Do not advise someone in matters outside your area of expertise. Whenever Ted, who is a lawyer, tried to give Bob suggestions about how to write his novel, Bob would say, "Let the cobbler stick to his last." Bill: I don't think you should put so much oregano in the spaghetti sauce. Nancy: You're a construction worker, not a chef. Let the cobbler stick to his last.

See also: his, last, let, stick