Ibrahim (may Allah have mercy on him) said: "If a man has four wives and he divorces one of them, he should not marry a new wife until her waiting period ('iddah) is completed. But if a wife dies, he may marry immediately, because death is not like divorce."
Hadith Referenceسنن سعید بن منصور / كتاب الطلاق / 2921
Hadith Takhrij«أخرجه سعيد بن منصور فى «سننه» ترقيم الدرالسلفية برقم:، 1742، 1743، وابن أبى شيبة فى «مصنفه» برقم: 17016»