In the beginning of his married life, Rav Shach and his family rented an apartment in Yerushalayim from Reb Alter Shub. Although Rav Shach paid rent for his living quarters, he nonetheless felt gratitude towards the Shub family for conferring this beneﬁt to him. Rav Shach considered it his duty to treat the Shub family exceptionally well, even extending this treatment to the family’s offspring.
Many years after Rav Shach moved to Bnei Brak, it happened that some of Reb Alter Shub’s grandchildren found themselves in Bnei Brak late one evening, without means of transportation available to take them home to Jerusalem.
Rav Shach was overjoyed to host them in his home for the night as a way of expressing his gratitude to his “landlord,” as he referred to Reb Alter.
Rebbetzin Guttel Shach later quietly told the guests that Rav Shach had been planning to go out somewhere that night, but because of the mitzvah of hospitality and Hakaras Hatov (gratitude) that had come his way, he had stayed at home.
Path to Greatness by Rabbi Asher Bergman, Published by Feldheim, page 486