Ibn Abi Mulaykah (may Allah have mercy on him) says that whenever Sayyiduna Ibn Umar (may Allah be pleased with them both) conducted a marriage, he would say: I marry you as Allah Almighty has commanded: "Either releasing (her) with good treatment or retaining (her) in kindness" [Surah al-Baqarah: 229].
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13833