One body (εν σωμα). With the harlot. That union is for the harlot the same as with the wife. The words quoted from Genesis 2:24 describing the sexual union of husband and wife, are also quoted and explained by Jesus in Matthew 19:5 which see for discussion of the translation Hebraism with use of εις.

Saith he (φησιν). Supply either ο θεος (God) or η γραφη (the Scripture).