If he divorces his wife three times before consummation, it counts as one

Tawus (may Allah have mercy on him) and Ata (may Allah have mercy on him) said: If a man gives his wife three divorces before consummating the marriage, one divorce takes effect.

Tawus (may Allah have mercy on him) said: Once Abu al-Sahba came to Sayyiduna Ibn Abbas (may Allah be pleased with them both) and said: "Tell us some of your rare pieces of knowledge: three divorces were counted as one in the time of the Messenger of Allah (peace and blessings be upon him), then in the time of Sayyiduna Abu Bakr (may Allah be pleased with him), and then in the early period of Sayyiduna Umar (may Allah be pleased with him). Then, when Sayyiduna Umar (may Allah be pleased with him) saw that people had made pronouncing divorce a habit, he made the three divorces count as three."

Tawus, Ata and Jabir bin Zayd said: When a man gives his wife three divorces before consummating the marriage, they count as only one.