We must supply the omitted verb edi(9378)a (pursued) from
verse  31 . That explains the rest. {They stumbled at the stone
of stumbling} (prosekopsan t(9369) lith(9369) tou proskommatos). The
quotation is from  Isa 8:14 . Proskopt(935c) means to cut (kopt(935c))
against (pros) as in  Mt 4:6  Joh 11:9f . The Jews found Christ
a skandalon ( 1Co 1:23 ).