A phrase said to someone who is ill or injured meaning “take care of yourself” or “get well soon”; commonly used when parting or at a hospital.
風邪を引いた同僚に『お大事に』と言ってメールを送った。
I sent an email telling my colleague who caught a cold to 'take care'.
診察が終わって帰るとき、看護師さんに『お大事にしてください』と言われた。
After the check-up, the nurse told me 'please take care'.
怪我をしたと聞いて、『お大事にね』と声をかけた。
When I heard about the injury, I said 'get well soon'.