First of all, it is to be stated that Muslims who utter three divorce pronouncements at one time or in one statement are rebels against Allah’s law and are deviating from the straight path of Islam.
As for the ruling on the triple divorce and whether it is counted as one divorce or three, Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
“As for the question: Whether the triple divorce pronounced concurrently by the husband shall be considered as a single divorce or three separate divorces. If it is considered as three separate divorces, then the couple cannot be married again unless someone else has married the woman, and he has, on his own free will, divorced her.
according to scholars such as Ibn Taymiyyah and Ibn al-Qayyim, triple divorces that are pronounced concurrently shall be considered only as a single divorce. They base themselves on the evidence that it was treated by the Prophet (peace and blessings be upon him) as single divorce. It is further supported by other clear evidences from the Qur’an and the Sunnah.”
Shedding more light on the issue, we’d like to cite the words of Sheikh Sayyed Sabiq in his well-known book, Fiqh As-Sunnah. He writes:
“Muslim scholars maintain that the one who divorces his wife three times in one occasion has committed a sin. It is reported that the Prophet (peace and blessings be upon him) became very angry when he was informed that a man had divorced his wife by pronouncing it three times on one occasion.
however, jurists differ as to whether the divorce pronounced three times in succession is to be counted as one divorce pronouncement or three separate divorces. The majority of scholars state that if the husband pronounces the divorce of his wife three times on one occasion, it will be counted as three divorces. This is the opinion of many of the Prophet’s Companions, the majority of the successors, and the imams of the four schools of fiqh.
Other scholars including Ibn Taymiyyah, Ibn al-Qayyim are of the opinion that it should be counted as only one pronouncement of divorce. This is also reported by Ibn al-Munzir from `Ata’, Tawus, Ibn Dinar. Ibn Mughith also reported this opinion of `Ali ibn Abi Talib, Ibn Mas`ud, `Abdur-Rahman ibn `Awf, Az-Zubayr from among the Companions of the Prophet (peace and blessings be upon him).
they quote the following hadith in support of their view: “Ibn `Abbas (may Allah be pleased with him) reports that the (pronouncement) of three divorces during the lifetime of Allah’s Messenger (peace and blessings be upon him) and that of Abu Bakr (may Allah be pleased with him) and two years of the caliphate of `Umar ibn Al-Khattab (may Allah be pleased with him) was treated as once. But `Umar ibn Al-Khattab (may Allah be pleased with him) said: “Verily the people have begun to hasten in the matter in which they are required to observe respite. So if we had imposed this upon them (i.e. regard the divorce pronounced three times in succession as irrevocable divorce, it would have deterred them from doing so)!” So he regarded it as such. This latter view is believed to be the most correct.”