Hajjaj bin Muhammad al-Musaysi حجاج بن محمد المصيصي الأعور · The Book on Marriage

He (Abu Qilabah) said: "If I wish, I could say: 'The Messenger of Allah said'" but he said: "The Sunnah when a man married a virgin after he already has a wife, is that he stays with her seven (nights). And when he married a matron when he already has a wife, he stays with her three (nights)."