Ali bin Husayn (may Allah have mercy on him) said that when a man says: "On the day I marry so-and-so, she is divorced", nothing at all is due from him.
(b) Al-Hasan bin Rawah al-Dabbi said: I asked Sa'id bin al-Musayyib, Mujahid and Ata (may Allah have mercy on them) about a man who says: "On the day I marry so-and-so, she is divorced", and nothing at all is due from him. And Sa'id bin al-Musayyib (may Allah have mercy on him) said: "O my nephew! Does a flood come before the rain?"
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 14891