grep to show date/time of file the string was found in.

I've seen several examples of grep showing the filename the string was found in, but what I really need is grep to show the file details in long format (like ls -l would).
scenario is:
grep mobile_number todays_files

This will show me the string I'm after & which files they turn up in, but the string could show in several files, so being able to see the time the files were created & in time order would be handy in identifying the order of events rather than having to �ls -l� all the identified files after.
Eg
broken, still broken, fixed (good)
fixed, broken, still broken (bad)
I have tried combination of "-exec ls -ltr {} \;" but don't seem to be getting anywhere.

Try:

grep -l searchstring filename(s) | xargs ls -l

Thanks SFNYC. Just what I was after. Stick a �t� on the end & I can now see what happened to the numbers & in what order.