It is narrated from Amir al-Sha'bi, concerning a man who declares his wife forbidden to himself, that he said: "They say that Sayyiduna Ali (may Allah be pleased with him) counted it as three divorces." Amir said: "Sayyiduna Ali (may Allah be pleased with him) did not say this; rather he said: 'I neither declare her lawful nor declare her forbidden.'"
It is reported from Sayyiduna Ali (may Allah be pleased with him) that if he intends it, three divorces take effect. However, this is a weak narration.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 15069