Musnad Abu Ya'la al-Mawsili 112:7

Suwayd ibn Sa'id narrated to us, Abu Mu'awiyah narrated to us, from Isma'il, from al-Hasan, from Anas ibn Malik, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "The likeness of my companions is the likeness of salt in food; food is not made right except with salt."