Sa'id bin al-Musayyab (may Allah have mercy on him) said that Sayyiduna Abu al-Darda' (may Allah be pleased with him) said regarding ila: After four months have passed he will be made to stand: either he divorces or he takes her back.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الإيلاء / 15222