Imam al-Shafi'i (may Allah have mercy on him) says concerning the saying of Allah Almighty: "If they intend reconciliation" [Surah al-Baqarah: 228], that the reconciliation of divorce is taking back (raj'ah). [Sahih]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرجعة / 15147