What is Iman?

Assalamu'alaikum Warohmatullohi Wabarakatuhu...
Bismillaahirrohmaanirrohiim

Once a Man asked the Prophet Sallallahu "Alaihi wa Sallam. What is
Iman? and He replied, When your good deeds make you happy and your bad
deeds make you sad, you have Iman. (Ahmad). Subhanallah…///