Ja'far bin Muhammad narrates from his father that Sayyiduna Ali (may Allah be pleased with him) used to say regarding ila: When four months pass and the one who took the oath of ila has not been made to stand, that is not a divorce; even if a year passes there will be no divorce, until the one who took the oath of ila is made to stand.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الإيلاء / 15215