What exactly did Yahshua/Jesus do during his 40 day fast after being baptized?

It is stated in the Gospels of Matthew, Mark, and Luke that during the 40 day period Christ was tempted by The Devil/Satan but not many other details are given. In the book of Isaiah (Isaiah 58:1-12 ), the Prophet Isaiah highlights what a pleasing and acceptable fast is according to The Creator. In order for his fast to be acceptable unto The Creator, what was Yahshua/Jesus doing during that period? Are there any stories, commentaries, articles, and/or resources that highlight or discuss what was going on during his 40 days? Thank you.