Sayyiduna Anas (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "When a man marries a virgin while he has a previous wife, he should spend seven nights with her; and when he marries a previously married woman while he has a virgin wife, he should spend three nights with her."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب القسم والنشوز / 14763