Answer:
In saying this phrase, President Washington refers to the non-politicization of the armed forces, that is, the non-interference of the military forces in American politics. His fear was that the military would take a political power superior to that of society itself, threatening the country's own democracy due to the risk of a coup d'etat that violated the individual liberties of its citizens.
For this reason, Washington pretended that politicians did not give said power to the military, limiting their participation and therefore their influence on democratic issues.
