Musnad Ahmad 25:871

'Abd al-Rahman ibn Mahdi narrated to us, he said: Shu'bah narrated to us, from 'Ata' ibn al-Sa'ib, from Sa'id ibn Jubayr, from Ibn 'Abbas: That the Prophet, peace and blessings of Allah be upon him, was brought a bowl of tharid (a dish of bread and broth). He said: "Eat from its sides, and do not eat from its middle, for the blessing descends in its middle."