The Concept Of Law by H. L. A. Hart*
From page 168...
"Moral and legal rules of obligation and duty have [therefore] certain striking similarities enough to show that their common vocabulary is no accident. They may be summarized as follows. They are alike in that they are conceived as binding independently of the consent of the individual bound and are supported by serious social pressure for conformity; compliance with legal and moral obligations is regarded not as a matter for praise but as a minimum contribution to social life to be taken as a matter of course. Further
both law and morals include rules governing the behaviour of individuals in situations constantly recurring throughout life rather than special activities or occasions, and though both may include much that is peculiar to the real or fancied needs of a particular society, both make demands which must obviously be satisfied by any group of human beings who are to succeed in living together..."
(my emphasis)
*
https://en.wikipedia.org/wiki/The_Concept_of_Law