23 And if they do not persist in unbelief, they will be grafted in, for God is able to graft them in again.

Read Romans 11:23 Using Other Translations

And they also, if they abide not still in unbelief, shall be graffed in: for God is able to graff them in again.
And even they, if they do not continue in their unbelief, will be grafted in, for God has the power to graft them in again.
And if the people of Israel turn from their unbelief, they will be grafted in again, for God has the power to graft them back into the tree.