The Caliph Ma’mun had a dream wherein he was inside the Ka’aba. He urinated at two of the corners inside of it and later on he did the same outside of it at the two other corners. He felt ashamed of this dream, but still wanted to know its meaning.
He told one of his servants to go to the famous Ibn Sirin and tell him the dream while pretending it was a dream of the servant. Ibn Sirin, however, made it clear that it had to be a dream of a member of the family of the caliph who had to come himself and tell the dream.
When Ma’mun came and told his dream, Ibn Sirin told him that the meaning of the dream was that he would get four sons, two of whom would succeed him as caliph.