In the paper that I am writing, I am only showing some results from a more rigorous/full-scale study. So as to highlight the importance of the results in the new paper, I am thinking of including one or two statements which state the full results that we have obtained (not published).
However, I can't include all the results from the full-scale study in this paper, because of size limitations. So is it appropriate to include these one or two sentences which demonstrate the results of the full scale study, but not include any data supporting these sentences in the abstract and summary?
I don't think so. Unless you have another published paper that you can refer to, I wouldn't put anything about the full result in this paper nor its abstract. Since you don't have that paper (yet?), there's no good way to refer to such a result without a way to back it up.