Many are the sources from which friendships are made. Leaving out all unlawful ones, we shall speak only of those which are natural and moral; the natural are, for instance, between father and son, brother and brother, and such like; which He meant, saying, Nor thy brethren, nor thy kinsmen; the moral, when a man has become your guest or neighbour; and with reference to these He says, nor thy neighbours.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Hom. 1, 3. in ep. Col.