ξένος ὢν ἀκολούθει τοῖς ἐπιχωρίοις νόμοις → as a foreigner, follow the laws of that country | when in Rome, do as the Romans do
3ᵉ pl. impf. épq. et ion. de εἶμι.
ἤϊσαν: эп.-ион. (= ᾖεσαν) 3 л. pl. impf. к εἶμι.