Why is this praise applied to the Jewish people specifically at the time
when they are Oleh l'Regel -- what is the connection between going to
Yerushalayim at the time of the festival, and being referred to as the
"daughter of Avraham?" Furthermore, why is Avraham Avinu referred to in this
context as "Nediv," the first to convert?
(a) The MAHARSHA explains why the Jewish people are praised as the daughter
of Avraham Avinu when they are Oleh l'Regel. Besides being the first of
converts, he was also the first to go up to the place of the Mikdash (Har
ha'Moriyah) in order to offer a Korban (his son, Yitzchak). The Jewish
people follow in his ways when they go to offer Korbanos in the Mikdash on
the festival.
The Maharsha does not explain, though, why the Gemara mentions the praise
that Avraham was the first of converts. The ETZ YOSEF explains that for
Avraham, converting entailed separating himself from his homeland and his
father's household in order to travel to a distant land (c.f. Bereishis
12:1). In that sense, the people who are Oleh l'Regel are similar to
converts; they separate themselves from their households, leaving everything
behind in order to go to the Beis ha'Mikdash in Yerushalayim.
(b) The CHIDA (in Pesach Einayim) suggests that our Gemara is based on the
Midrash BEREISHIS RABA 43:9. The Midrash states that as reward for refusing
to accept from Malki-Tzedek "a thread ('Chut') or a shoestrap ('Seroch
Na'al')," Avraham was blessed that his descendants offered Korbanos on the
Mizbe'ach (which was encircled with a "Chut" -- painted strip -- of red dye)
and were given the Mitzvah of Aliyah l'Regel. The Midrash goes on to quote
the verse cited by our Gemara, "Ma Yafu... *ba'Ne'alim*."
(This, again, explains why the Mitzvah of Aliyah l'Regel is related to
Avraham, but not why Avraham is referred to as "the first of converts" in
this context.)
(b) The Gemara in Berachos (17b) states that shortly before Pesach and
Sukos, when the Jews in Bavel would gather together to learn Torah at the
"Yarchei Kalah" in order to prepare for the festival, a great Kidush Hashem
occurred. There was a tremendous inspiration for the surrounding nations to
come and convert when they saw the immense glory of Hashem as everyone
gathered together in a large assembly to learn Torah in preparation to
perform the Mitzvos of the festival.
The Midrash (Midrash Rabah to Shir ha'Shirim 1:15) compares the Jewish
people to a Yonah, a pigeon, in several ways. One reason the Jewish people
are compared to a Yonah is because there is a type of Yonah which, when fed,
gives off a scent that attracts other pigeons to its nest. Similarly, when
the Chachamim gather the people to teach Torah, the nations who hear of them
come and convert.
In a similar vein, Rashi comments on the verse in the blessing given to the
tribe of Zevulun, "Amim Har Yikra'u" -- "Nations will gather at the
mountain" (Devarim 33:19) that these "nations" refer to the Jewish people
who gather at "the mountain" of Har ha'Moriyah and offer Korbanos to Hashem
on the Regalim. It also refers to the nations of the world who come to Eretz
Yisrael to do business, and while there gather at Har ha'Moriyah and see the
Jewish people gathered there serving Hashem. They become so impressed that
they convert. Combining the two Derashos, we may infer that they come at the
time that the Jews are Oleh l'Regel, and that is when the great assembly of
Jews performing the will of Hashem in unison makes an impression on them and
they convert (as seen from the above-quoted Midrashim).
When the Jewish people conduct themselves in a way which inspires the
nations to convert, they are referred to as "the daughter of Avraham," who
was the first to convert and to inspire others to follow him (c.f. Bereishis
12:5). That is why the Gemara quotes the verse, "The noblemen of the nations
gathered [to join] the nation of the G-d of *Avraham*" (Tehilim 47:10) --
i.e. they gathered in order to become part of the Jewish people, to convert
(as the Maharsha explains) and follow in the ways of Avraham. Therefore,
when the Jewish people are Oleh l'Regel and inspire the nations to convert,
they are called "Bas Nediv," for they are following the ways of Avraham who
led the way for converts. (M. Kornfeld)