Jamieson, Fausset and Brown on Romans 11:22-23

22-23. Behold therefore the goodness and severity of God: on them that fell, severity--in rejecting the chosen seed.

but toward thee, goodness--"God's goodness" is the true reading, that is, His sovereign goodness in admitting thee to a covenant standing who before wert a "stranger to the covenants of promise" (Ep 2:12-20).

if thou continue in his goodness--in believing dependence on that pure goodness which made thee what thou art.