To sing in your dream represents happiness, harmony and joy in some situation or relationship. You are uplifting others with your positive attitude and cheerful disposition. Singing is a way to celebrate, communicate, embrace and express your feelings.
To hear someone sing in your dream signifies emotional and spiritual fulfillment. Your mood is changing for the positive as your outlook in life is looking up. In particular, dreaming that an enemy is singing to you means that you need to reevaluate the negativity you have towards the enemy. Perhaps it is time to let go of the animosity or some of the feelings you are harboring.