Musannaf Ibn Abi Shayba 19:340

Abu Bakr narrated to us, he said: Yazid bin Harun narrated to us, he said: Imran bin Hudair narrated to us, from al-Sumayt bin Umayr, who said: A man entered the mosque on a Friday and prayed four [rak'ahs]. A man said to his companion, "Did you see what I saw?" He said, "Yes." So they took him and brought him to Abu Musa al-Ash'ari. They said, "This man entered the mosque and prayed four." He said, "Did he change [the prayer]?" They said, "No." He said, "This is indeed a suspicion." He said [to the man], "What drove you to what you did?" He said, "I had not drunk it before today." So he flogged him eighty [lashes].