Well it's up to you but it can give you food poisoning.
The advice from the food standards agency is as follows :
There are a few things to remember when you are storing and reheating cooked rice and grains. This is because the spores of some food poisoning bugs can survive cooking.
If cooked rice or grains are left standing at room temperature, the spores can germinate. The bacteria multiply and produce toxins that can cause vomiting and diarrhoea. Reheating food won't get rid of the toxins.
Therefore, it's best to serve rice and grains when they've just been cooked. If this isn't possible, cool them within an hour after cooking and keep them refrigerated until reheating or using in a cold dish.
You should throw away any rice and grains that have been left at room temperature overnight.
Don't keep cooked rice and grains for longer than two days and don't reheat them more than once. Check the 'use by' date and storage instructions on the label for any cold rice or grain salads that you buy.