Musnad Abu Ya'la al-Mawsili 148:39

Abu al-Rabi' al-Zahrani narrated to us, Hammad narrated to us, he said: I heard Hanzalah ibn 'Abd Allah say: I heard Anas ibn Malik say: It was said: "O Messenger of Allah, should we bow to one another when we meet?" He said: "No." I said: "Should we embrace one another?" He said: "No." He said: "Should we shake hands with one another?" He said: "Yes."