The Prophet (peace be upon him) explained these in a succinct and clear way while addressing his Lord, "You are the First, there was none before You. You are the Last, there will be none after You. You are the Manifest, there is nothing above You. You are the Inward, there is nothing closer than You."
“He is the First, the Last, the Manifest and the Inward. He is the All-Knower of everything.”
[al-Hadid (57): 3]
From “Explanation to the Beautiful and Perfect Names of Allah” — Shaykh as-Sa’di (d.1376H)