Muhammad bin Abd al-Rahman bin Thawban narrates from Muhammad bin Iyas bin al-Bukayr that a man divorced his wife three times before consummating the marriage; then he decided to marry her, so he came seeking a fatwa, and I went with him to ask on his behalf. He asked Sayyiduna Abu Hurayrah (may Allah be pleased with him) and Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) about this, and both of them said: We do not think that you may marry her until she marries another husband. He said: My divorce of her was only one. Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: You have let go from your own hand the extra divorces that were yours.
(b) Mu'awiyah bin Abi Ayyash al-Ansari narrates from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that he both permitted the three divorces and enforced them.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 14982