To be dreaming of your friend singing to you, or singing where you are able to hear him/ her, has significance. The song’s lyrics maybe a message to you. Under normal circumstances, speech may not be communicate because the opposite party may not feel at ease to be frank. You could have received stimuli that your friend may be favorable to develop your friendship farther. This raw data was processed in your brain which triggered the creation of a dream.
Can you remember the song’s lyrics? What was the song about? The song was chosen for a particular reason, to communicate a message to you.
After waking up, reflect on your dream. Do you think the message was relevant and can be true? You might like to try talking to that friend in real life. You might hint at the theme of the message and see the feedback. Does it confirm your dream interpretation?