Musannaf Ibn Abi Shayba 3:4184

Hushaym narrated to us, from Yunus, that Ibn Sirin said: I went out with Anas to the Banu Sirin in a large ship. He said: So he led us in prayer, and he prayed two rak'ahs with us in it while sitting, then he prayed another two rak'ahs with us.