tend your knitting/tend to your knitting

The Running Manから今日取り上げるのはやはり単語ではなく慣用句です。
"..I'm Flight Captain Don Holloway. This is my co-pilot Wayne Duninger."
"Under the circumstances, not very pleased to meet you." Duninger said.
Richards's mouth quirked. "In the same spirit, let me add that I'm sorry to be here. Captain Hollowy, you're patched into communications with McCone, aren't you?"
"We sure are. Through Kippy Friedman, our communications man."
"Give me something to talk into."
Holloway handed him a microphone with infinite carefulness.
Get going on your prefilight," Richards said. "Five minutes."
"Will you want the explosive bolts on the rear loading door armed?" Duninger said with great eagerness.
"Tend your knitting," Richards said coldly.
最後に出てきた台詞 "Tend your knitting" も慣用句としての意味を知らなかったので、唐突に何の話かと思いました。辞書を見ると次の意味であることが分かりました。
・Oxford English Dictionary: (Of a person or an organization) concentrate on a familiar area of activity rather than diversify; mind one’s own business.
・Dictionary.com: stick/tend to one's knitting,
a.to mind one's own business: Don't worry about my work?just tend to your knitting.
b.to devote oneself to one's assignments or responsibilities: Years of sticking to his knitting finally paid off.
Richardsは "Tend your knitting" と言っていますが、 "Tend to your knitting" の方が正しい英語でしょう。