Just return it as action method return value.
public String action() {
return "another.xhtml";
}
If you're in turn not doing anything else than navigating, then you could also just put the string outcome directly in action
attribute.
<h:commandButton action="another.xhtml" value="Go to another page" />
However, this is in turn a rather poor practice. You should not be performing POST requests for plain page-to-page navigation. Just use a simple button or link:
<h:button outcome="another.xhtml" value="Go to another page" />