Find all scripts with a given shebang line with find & sed

I want to find out all scripts with a specific shebang line. Specifically, I want all files that match the following criteria: * It's mostly a plain text file (stuffs created by gzexe don't look very friendly) * The 1st line contains solely #!/bin/sh or #! /bin/sh (with a space) I would like to do this with find, sed and grep (file available). File names are useless, because some scripts don't have extensions or even have wrong extensions. Also a something.sh may have a shebang line of #!/bin/bash which is also not what I wanted. Besides, sometimes I would come across a file like this:

#!/bin/sh
blah.blah.blah...

The 1st line is empty and the shebang is located at the 2nd line, which **is not what I wanted**. I am able to find shebang lines with find|grep but I don't know how to find lines **specifically on the 1st line** of a file. Thanks for any help in advance.