Who are "Abirei Lev"?
Brachos 17b #1: This refers to a foolish nation (descendants of the Giv'onim 1 ) in Bavel. Not one of them ever converted!
Brachos 17b #2: They are the residents of Masa Mechasya. They see the honor of Torah twice every year ( when the Chachamim gather to learn the laws of the festival), yet none of them ever converted.
Rashi: They are Yisrael. I strengthened your hearts, and you clung to Me!
Radak, Malbim: They are Anshei Bavel. They are strong-hearted, and cruel to Yisrael.
Maharsha (17a): Many Giv'onim converted in the days of Yehoshua; these descend from those who did not convert.
What do we learn from "ha'Rechokim mi'Tzedakah" ?
Brachos 17b #1: The entire world is fed through Tzedakah, except for them -- they are fed through their own merit.
Brachos 17b #2: The entire world is fed in their merit, they are not fed even in their own merits (they struggle to obtain their needs). E.g. the entire world is fed in the merit of R. Chanina ben Dosa, yet he subsists on one Kav of carobs for an entire week!
Rashi: Your days [in Galus] were lengthened, and I did not show to you My Tzedakah to redeem you. .
Radak: Anshei Bavel are far from doing Tzedakah for Yisrael.
Malbim: Tzedakah is close
