The teachings have been heard to love your enemies, because otherwise, what would be the big deal to love those who love you, that would be easy ... or thereabouts in paraphrase, and so forth so on. But this kind of teaching is crude and unevolved. There are many, many people who have self-loathing and cannot come to love themselves, for whatever psychophysical reasons. The assumption that people love those who love them is naive, even as those who have self-loathing would psychically vampirize those who love them. It's like the Woody Allen joke, about not wanting to belong to any club that would have them as a member.
The primary essential of ethics is to learn to love one's own self and to be reconciled in the love of those who indeed do love them; this indeed is the primary foundation, for as an old song says, how can you say you love someone when you don't even love yourself? The next phase is those who are closest, immediate family. There are many who do not love their own progeny, as they do not love themselves; how could they love their progeny if they do not love themselves? And of course society is rife with the ills that spread from people a priori not loving themselves.