How to get the last modification date of a file in a git repo?

I'm trying to find a command to get the last modified date of a file in a local git repo.

I have created the repo and done one commit. I only had to edit one file and will commit it, but I was wondering what the last modification data of the file in the repo is (not the commit date).

I only have the command line, and git log ./path/to/filename.php only gives me the commit date