Some of the advice on this thread is wrong or incomplete. Lonecatwithkitten is right. If you have a court order stating that the child lives with you, you can take the child out of the country for up to 28 days.
If you do not have a court order and the NRP has PR you need their consent to take the child out of the country otherwise you are committing a criminal offence. Having said that, it is highly unlikely you would be prosecuted for taking the child out of the country for a short time. Many people go abroad without the necessary consent. However, some find that they are refused entry at their destination because they can't show that they have the consent of the other parent.