Musannaf Ibn Abi Shaybah 36737 — Reports on the description

It is narrated from Sayyiduna Anas (may Allah be pleased with him) that Sayyiduna Abdullah bin Salam (may Allah be pleased with him) came to the Prophet (peace and blessings be upon him) in Madinah and asked: "What is the first thing the people of Paradise will eat?" The Prophet (peace and blessings be upon him) said: "Jibril (peace be upon him) has just informed me that the first food of the people of Paradise will be the extra lobe of a fish's liver."
Muhammad bin Ka'b said: "Something like lightning is seen in Paradise. It is asked: 'What is this?' It is said: 'A man from the people of Illiyyin moving from one chamber to another.'"