More formal options:
* "Please find attached the translated document, ready for stamping."
* "For your review and stamping, please find the translated document attached."
* "Attached is the translated document, which is ready for stamping."
More informal options:
* "Attached is the translated document. Please stamp it when you get a chance."
* "I've attached the translated document. Could you please stamp it?"
The best option depends on your relationship with the recipient and the overall tone of your communication.