Romans 11:23
And these Jews also will be grafted [back] in [to the olive tree] if they do not continue in their lack of faith [in Christ], because God is able to graft them back in again.
Romans 11:26
And so [i.e., in this way] all the Israelites will be saved. [Note: The "all" here is thought by many to refer to a large number of the physical Jews who will be saved, not necessarily to every single individual Jew]. Even as it is written [Isa. 59:20-21], "The Deliverer [i.e., Christ] will come from Zion [i.e., the city of Jerusalem, or from the nation of Israel]. He will take away the wickedness from Jacob [i.e., the Jews]."
Romans 11:31
So, now these [same] Jews have also been disobedient [to God], so that they may also now obtain [God's] mercy by means of the mercy [He has] shown to you [Gentiles].