Elsewhere in Scripture, Sarah is connected with the Abrahamic covenant and Mount Zion (Isaiah 51:1–3). Zion represented the heavenly Jerusalem, the dwelling of God with his people (Psalm 87:1–7). Hagar is not connected to Zion but to Sinai in Arabia, a mountain outside the Promised Land,1 not the dwelling place of God with his people.
25 Now Hagar is Mount Sinai in Arabia; she corresponds to the present Jerusalem, for she is in slavery with her children.