Galatians 4:24
These things are being taken as figurative, for the women represent two covenants. One covenant is from Mount Sinai and bears children who are to be slaves: This is Hagar. — Paul's allegorical reading assigns the two women cosmic significance: Hagar represents the Sinai covenant ('diathēkē apo orous Sinai'), which produces 'teknon doulos' (children destined for slavery), the enslaved progeny of law-observance.