Show specific git commit

git show <revhash>

will show the commit date, author, parent, and diff of files that changed from parent commit

Your reflog can be viewed too - for example, the last commit can be seen with:

git show HEAD

One more back?:

git show HEAD~1

To view a particular file only, use:

git show <revhash>:/path/to/file

To get specific information about a commit object:

git cat-file commit <revhas>