{How that it is an unlawful thing} (h(9373) athemiton estin).
The conjunction h(9373) is sometimes equivalent to hoti (that).
The old form of athemitos was athemistos from 	hemisto
(	hemiz(932c) themis, law custom) and a privative. In the N.T.
only here and  1Pe 4:3  (Peter both times). But there is no O.T.
regulation forbidding such social contact with Gentiles, though
the rabbis had added it and had made it binding by custom. There
is nothing more binding on the average person than social custom.
On coming from the market an orthodox Jew was expected to immerse
to avoid defilement (Edersheim, _Jewish Social Life_, pp. 26-28;
Taylor's _Sayings of the Jewish Fathers_, pp. 15, 26, 137, second
edition). See also  Ac 11:3  Ga 2:12 . It is that middle wall of
partition between Jew and Gentile ( Eph 2:14 ) which Jesus broke
down. {One of another nation} (allophul(9369)). Dative case of an
old adjective, but only here in the N.T. (allos, another,
phulon, race). Both Juvenal (_Sat_. XIV. 104, 105) and Tacitus
(_History_, V. 5) speak of the Jewish exclusiveness and
separation from Gentiles. {And yet unto} (kamoi). Dative of the
emphatic pronoun (note position of prominence) with kai
(crasis) meaning here "and yet" or adversative "but" as often
with kai which is by no means always merely the connective
"and" (Robertson, _Grammar_, pp. 1182f.). Now Peter takes back
both the adjectives used in his protest to the Lord (verse  14 )
"common and unclean." It is a long journey that Peter has made.
He here refers to "no one" (m(8864)ena), not to "things," but that
is great progress.