Not sure if this is what she is referring to...

Matt 11:19-23
The Unrepenting Cities
20 Then He began to denounce the cities in which most of His miracles were 
done, because they did not repent.
21 "Woe to you, Chorazin! Woe to you, Bethsaida! For if the miracles had 
occurred in Tyre and Sidon which occurred in you, they would have repented 
long ago in sackcloth and ashes.
22 "Nevertheless I say to you, it will be more tolerable for Tyre and Sidon 
in the day of judgment than for you.
23 "And you, Capernaum, will not be exalted to heaven, will you? You will 
descend to Hades; for if the miracles had occurred in Sodom which occurred 
in you, it would have remained to this day.

Perhaps she can find the passage being this is her belief? Not for your 
sake necesarily in and of itself, but her own. That is to say that its best 
to lay foundational beliefs on biblical references we know rather than "I 
think it says somewhere in the bible that..." plus in these little searches 
we gain knowledge and gems along the way :).

Brad