What’s a Qareen

Ustadh Nouman Ali Khan divulges details when after the Day of Judgement when some are in Hell and others are in Heaven. From the perspective of a Heaven dweller, an insight is drawn asking about each other and it makes for an engaging listen. One of the Heaven dwellers remembers a friend from his life on earth whom we call as a Qareen.  What were the conversations between the Qareen and himself? And what was the repercussion of that conversation?