I am assuming you mean a quote from either movie that relates to both. One such quote that stood out to me from Schindler's List was a saying from the Talmud (Jewish holy text, law):
And whoever saves a life, it is considered as if he saved an entire world.
In the film it is inscribed (paraphrased) on a ring given to Oskar Schindler by the workers for his efforts to rescue them.
I think it relates to both movies because, even though at first glance, the hero of each story saved relatively few people compared to the hundreds of thousands of people massacred in Rwanda, or the millions murdered in the Holocaust, they also saved all of the descendants of those rescued, generations of people that make the quote seem particularly true.
At the end of Schindler's List, they march the several thousand children and grandchildren of the survivors past Oskar Schindler's grave, and the number is greater than the total number of Jews still living in Poland.