Musnad Ahmad 32:119

Ya'qub narrated to us, my father narrated to us, from Ibn Ishaq, Humayd al-Tawil narrated to me, from Anas ibn Malik, from Abdullah ibn Salam, who said: When I intended to embrace Islam, I came to the Messenger of Allah, peace and blessings of Allah be upon him, and said: "I am going to ask you." He said: "Ask about whatever appears to you." He said: I said: "What is the first thing the people of Paradise will eat?" Then he mentioned the hadith.