Every man and woman that is born has a demonic double also born in the world of hell ruled by Samael, the Evil One. The world of hell is in all respects identical to the world of humanity. If you were to look at your double, it would be as if you were staring at your own eyes in a mirror. Each person is appointed a soulmate by angels of heaven, and if the hands of fate are fortunate, the couple meet and form a happy union.
But woe to the person who is alone on the fourth night of the week, or on the Sabbath, because sons of Samael kidnap the person and force them to marry not their partner fated by heaven, but their demonic double.
https://www.matthewkressel.net/2015/09/19/36-days-of-judaic-myth-day-12-your-demonic-double/