Al-Matalib al-'Aliyah 1702 — The validity of a triple divorce in one

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that he said: "The woman with whom consummation has not yet taken place: when all three divorces are combined upon her at once, they take effect." Hasan bin Muslim says: Then I mentioned this to Imam Tawus (may Allah have mercy on him), and he said: I bear witness that I myself heard Sayyiduna Ibn Abbas (may Allah be pleased with them both) say that he counted it as only one divorce. Amr also said the same: it is one divorce, even if all three are combined (in words).
In this narration two different opinions are reported from Sayyiduna Ibn Abbas (may Allah be pleased with them both) regarding the ruling on three divorces given at once to a woman whose marriage has not been consummated: according to the first opinion all three take effect, whereas according to the testimony of Imam Tawus his other position was that it is counted as only one divorce.