Musannaf Ibn Abi Shayba 27:767

Hussain bin Ali narrated to us, from Abu Musa, from al-Hasan, who said: The Messenger of Allah (may Allah bless him and grant him peace) said to his companions: "You are among the people like salt in food." Then al-Hasan said: "And food is not made good except with salt." Then al-Hasan says: "What will become of a people whose salt has gone?"