Musannaf Ibn Abi Shayba 3:6104

Abu Bakr and Hushaym narrated to us, they said: 'Abd al-A'la narrated to us, from Ma'mar, from al-Zuhri, from Ibn al-Musayyib, who said: "Do you know of a prayer in which one sits throughout its entirety?" A man said: "One who catches a rak'ah of the Maghrib prayer, so he sits during all of them."