An abstract is a brief summary placed at the beginning of a scholarly article. It normally tells the reader things such as:

the subject;

the research question or problem;

the central argument;

the approach;

and sometimes the principal findings.

The abstract of article can itself states the point clearly.

It does not mean that the abstract is the entire article.

if we have examined the full article, we should preferably cite the specific passage in the article when making a detailed claim rather than relying unnecessarily on the abstract.