Sunan Abi Dawud Book 2, Hadith 226
The Prophet (ﷺ) said: The Imam should not pray at the place where he led the prayer until he removes (from there).
Abu Dawud said: 'Ata' al-Khurasani did not see Mughirah b. Shu'bah (This tradition is, therefore munqati', i.e. a link is missing in the chain).
When we would pray behind the Messenger of Allah (ﷺ), we liked to be on his right side. He (the Prophet) would sit turning his face towards us (and back towards the Ka'bah) (ﷺ).
The Prophet (ﷺ) said: When the Imam completes the prayer and sits (for reciting tashahhud), and then becomes defiled (i.e. his ablution becomes void) before he speaks (to someone), his prayer becomes complete. And those who prayed behind him also complete the prayer.