rivers of oil - used in sacrifices (Lev 2:1, Lev 2:15). Will God be appeased by my offering so much oil that it shall flow in myriads of torrents?
my first-born - (2Ki 3:27). As the king of Moab did.
fruit of my body - my children, as an atonement (Psa 132:11). The Jews offered human sacrifices in the valley of Hinnom (Jer 19:5; Jer 32:35; Eze 23:27).