Who were few in number?
Radak: The Avos and their children. Yakov said "va'Ani Mesei Mispar" (Bereishis 34:30).
What is the meaning of "Kim'at v'Garim Bah"?
Radak: They lived in the land for a short time, and needed to leave. Avraham needed to go to Egypt and Eretz Pelishtim due to famine, Yitzchak needed to go to Eretz Pelishtim 1 , and Yakov went to Egypt.
Malbim: They were few in number, quality 2 and strength. They were not natives, rather, strangers. Even so, Hashem promised the land to them!
Midrash Agadah (Behar 25) clearly says that Eretz Pelishtim is out of Eretz Yisrael, unlike Tanchuma (Toldah 6) which says that Hashem told Yitzchak not to leave Eretz Yisrael. (PF)
I.e. physical attributes such as authority or power. Spiritually, the Avos were the highest quality there is! (PF)
