$ sh -c echo hallo

$ sh -c "echo hallo"
hallo
$ sh -c "echo hallo    world"
hallo world
$ ssh localhost echo hallo world
hallo world
$ ssh localhost "echo hallo    world"
hallo world
$ ssh localhost sh -c \"echo hallo world\" 
hallo world
$ ssh localhost sh -c \"echo hallo   world\"
hallo world
$ ssh localhost sh -c "\"echo hallo   world\""
hallo world
$ ssh localhost sh -c "\"echo \\\"hallo   world\\\"\""
hallo   world