Dahhak bin Fairuz Dailami narrated that his father said:
'I came to the Prophet and said: 'O Messenger of Allah! I have become Muslim and I am married to two sisters.' The Messenger of Allah said: 'Divorce whichever of them you want.' " (PT)
English reference (PT): Vol. 3, Book 9, Hadith 1951 (PT)
Arabic reference (PT): Book 9, Hadith 2027 (PT)