.htaccess - Apache server loads page instead of applying rewrite rule -

i'm trying make website add trailing slash , rewrite uri html page. redirect xy.com/abc xy.com/abc/, , load xy.com/abc.html.

my .htaccess file looks this:

rewriteengine on rewritebase / rewriterule ^([a-z]+)$ $1/ [r] rewriterule ^([a-z]+)/$ $1.html [l] 

when try going xy.com/asd (non-existing page) redirects xy.com/asd/ , gives me proper 404 error.

when try page exists (xy.com/about), loads xy.com/about.html without redirecting @ all.

try code:

options -multiviews rewriteengine on rewritebase /  rewriterule ^([a-z]+)$ $1/ [r,nc,l]  rewritecond %{document_root}/$1.html -f rewriterule ^([a-z]+)/$ $1.html [l,nc]