Musannaf Ibn Abi Shayba 3:4187

Abu Bakr narrated to us, he said: Marwan bin Mu'awiyah narrated to us, from Humayd, he said: Anas was asked about praying in a ship. Abdullah bin Abi Utbah, the freed slave of Anas, who was sitting with us, said: "I traveled with Abu Sa'id al-Khudri, Abu al-Darda', and Jabir bin Abdullah." Humayd said: And he (Anas's freed slave) mentioned them by name. "Our Imam would lead us in prayer in the ship while standing, and we would pray behind him while standing, even though if we had wished, we could have docked and exited."