“Iblis sends his troops across the earth with the promise that whichever of his followers misguides a believer the most will be given a crown.
One shaytan (devil) comes back to Iblis and says, ‘I did not leave him until he divorced his wife.’ Iblis says, ‘You did nothing; he will marry another!’
Another one comes back to Iblis and says, ‘I did not leave him until he and his brother became enemies.’ Iblis says, ‘You did nothing; they will be reconciled!’
Then another one comes back to Iblis and says, ‘I did not leave him/her until he committed Zina (adultery, fornication).’ Iblis then says, ‘Well done (i.e you’ve made me proud)!’ Then Iblis seats that shaytan by his side and crowns him.”
[Al-Kaba’ir of Imam Adh-Dhahabi, The 10th Major Sin, The Book of Fornication and Adultery (Zina), Pg. 105]
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This is not authentic.
The authentic hadeeth states in the end that the praised on is the one who separates between the man and his wife and not the adulterer.