From 31 January 2021, all passengers arriving into Dubai from any point of origin (GCC countries included) must hold a negative COVID 19 PCR test certificate for a test taken no more than 72 hours before departure.

• UAE nationals are exempt from the above, but will be required to take a PCR test on arrival at Dubai airport. 
• Passengers arriving into Dubai from certain countries will be required to take another PCR test on arrival at Dubai International Airport (see the list of countries below).
• Passengers transiting through Dubai do not need a PCR test unless required by their final destination.
• Children under the age of 12 and passengers who have a moderate or severe disability are exempt from the COVID 19 PCR test.

Afghanistan, Angola, Argentina, Bangladesh, Brazil, Cambodia, Chile, Croatia, Cyprus, Czech Republic, Djibouti, Egypt, Eritrea, Ethiopia, Georgia, Ghana, Guinea, Hungary, Indonesia, India, Iran, Iraq, Israel, Ivory Coast, Jordan, Kenya, Lebanon, Malta, Moldova, Montenegro, Morocco, Myanmar, Nigeria, Nepal, Pakistan, the Philippines, Romania, the Russian Federation, Rwanda, Senegal, Slovakia, Somaliland, South Africa, South Sudan, Sudan, Syria, Tajikistan, Tanzania, Tunisia, Turkmenistan, Uganda, Ukraine, Uzbekistan, Vietnam, Zambia or Zimbabwe.

Source: https://www.emirates.com/my/english/help/covid-19/dubai-travel-requirements/tourists/