The Law Code of Nārada m1.12

m1.12

sāmādyupāyasādhyatvāc catuḥsādhana ucyate /
caturṇām āśramāṇāṃ ca rakṣaṇāt sa caturhitaḥ //

Because the four means, of conciliation and the rest, are adopted, it is said to have four means. Because it protects the four orders, therefore it is said to benefit four.