Hagar is said to represent the covenant from Mount Sinai, which would mean that she represents the Mosaic covenant (Exodus 19:1–25). Sarah would then represent the Abrahamic covenant (Isaiah 51:1–2). This is confirmed by the fact that Paul quotes from Isaiah 54:1 in Galatians 4:27, thereby linking Sarah to Jerusalem while also affirming that the time has come for the eschatological fulfillment of the covenant made with Abraham.1
24 Ces faits ont une valeur allégorique; car ces femmes sont deux alliances. L'une du mont Sinaï, enfantant pour la servitude, c'est Agar