Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates from the Prophet (peace and blessings be upon him) regarding the command to take her back.
Imam al-Shafi'i (may Allah have mercy on him) said: Nafi' is more reliable in narrating from Ibn Umar than Abu al-Zubayr, and the more reliable of two hadiths has the better claim to be followed where they differ; and Nafi' is supported by others among the reliable people of hadith. It was said to him (Ibn Umar): Was Ibn Umar's divorce in the time of the Prophet (peace and blessings be upon him) counted as one divorce? He said: What else, even if he was helpless? Meaning that it was counted as one; and the verse of the Qur'an also indicates this: "Divorce is twice; then either retain her in an acceptable manner or release her with kindness." [Surah al-Baqarah: 229]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 14930