Galatians 4:27-29

Moffatt(i) 27 For it is written, Rejoice, O thou barren who bearest not, break into joy, thou who travailest not; for the children of the desolate woman are far more than of the married. 28 Now you are the children of the Promise, brothers, like Isaac; 29 but just as in the old days the son born by the flesh persecuted the son born by the Spirit, so it is still to-day.