What are the implications of "ha'Kol Kol Yaakov, veha'Yadayim Yedei Esav"?
Rashi: Yitzchak's suspicion was aroused by the manner of speech of Yaakov 1 - in that he spoke softly (inserting the word "please" (27:19), whereas Esav tended to speak gruffly (See 27:31).
Rashi #2 (to Bamidbar 20: 16,20): When Yisrael wanted to pass through the land of Edom, Moshe sent a message to the king of Edom that HaSh-m had answered our prayers in Egypt with the Berachah that our father Yitzchak had blessed us; 2 to which the king replied with a threat to attack them - with the Berachah that Yitzchak blessed Esav. 3
Gitin 57b: "Ha'Kol 4 " - refers to the Emperor Hadrian, who killed in Alexandria of Egypt 1,200,000; "Kol Yaakov" - refers to the Emperor Vespasian, who killed 4,000,000 [others say 4,000,000] - in the town of Beitar; "veha'Yadayim Yedei Esav" - refers to the kingdom of Rome, which destroyed 'our house,' 5 burned our Heichal, and exiled us from our land.
Gitin 57b: "Ha'Kol Kol 6 Yaakov" teaches us that no Tefilah is answered that does not include the participation of a descendent of Yaakov; and no battle is won that does not include the participation of a descendent of Esav.
Yerushalmi (Ta'anis, 4:5): The voice of Yaakov cries out from what Esav did to Yaakov in Beitar.
Oznayim la'Torah #1: Yitzchak gave Yaakov the voice of Yaakov (Torah and Tefilah) and the hands of Esav (the strength to fight and win wars). Only he made it clear that the hands are theirs only when they are 'borrowed' from Esav, 7 and are not to be used freely to engage in warfare. 8
Bereishis Rabah (65:20): 'When the voice of Yaakov is heard in the Batei Keneisiyos (in Torah and Tefilah), the hands are not the hands of Esav (Malbim - rather, then also Yaakov has Esav's hands, i.e. physical strength, wealth and authority). When his voice is not heard, then the hands are the hands of Esav. 9
Oznayim la'Torah #2: When the voice of the youth is heard studying Torah in the Batei Keneisiyos then the hands are the hands of Esav. But when they do not, their hands are the hands of Esav - when they indulge in sport (and other activities that belong to Esav) and HaSh-m does not recognize us. 10
Maharam Shif (Gitin 57b): It seems that the text should say 'when there is the voice of talebearers in Yaakov, the hands of Esav (overpower). In the days of Sha'ul, Yisrael were Tzadikim, but hey fell because there were talebearers.'
"ha'Kol Kol Yaakov!"
"V'Al Charbecha Sichyeh (27:40). Mechilta Beshalach ('va'Yehi' 2) cites also "veha'Yadayim Yedei Esav."
Rashi (ibid): The voice is of Yisraelim screaming and crying. Yitzchak saw all this through prophecy. Maharsha - This was Midah k'Neged Midah; Yaakov was afraid lest he be recognized through his voice or hands.
Alei Tamar (Ta'anis 4:6): The Mikdash (including the Azaros) was destroyed, but only the Heichal was burned.
Maharsha (to Gitin 57b): "Kol" is repeated, to teach that it must be like Yaakov's voice, i.e. supplication.
See Oznayim la'Torah, who elaborates on this point.
Oznayim la'Torah: Today's youth, believing that our problem lies in the fact that we overplay the Kol Yaakov, and do not adopt the Yedei Esav at all, have gone to the other extreme and built an army, turning the Yedei Esav into the Ikar, often at the expense of the Kol Yaakov - See Oznayim la'Torah, who elaborates on this point.
Oznayim la'Torah: That rule over us, Chas v'Shalom.
Oznayim la'Torah: As the Torah hints in the next Pasuk ,"v'Lo Hikiro, Ki Hayu Yadav ki'Yedei Esav, Se'iros" (27:23).
Why is Yaakov's greatness expressed in his 'voice,' whereas that of Esav is expressed in his 'hands'?
Gur Aryeh (to Bamidbar 21:35): 'Voice' is intangible; the power of Yaakov is to connect to HaSh-m, Who is intangible. In contrast, Esav's physicality is expressed though the hands, a person's ability to spread out, which is the nature of a physical entity. 1
Maharal (Ohr Chadash, p. 113): Yaakov is inward and modest, just as one's voice emanates from within. In contrast, Esav is out in the open, all external, just as the hands protrude outwards. 2 Ultimately, the inward strength of Yaakov prevails.
We may explain that the hands act and create, thus expanding a person's influence. All physical entities have three dimensions, whereas the spiritual does not have these dimensions. (EK)
Maharal: This is also reflected in the order of their birth - Esav emerged first, while Yaakov still remained within.
If Yitzchak recognized Yaakov's voice, why did he conclude that it must be Esav, and proceed to bless him?
Rashbam: the fact is that, being twins, their voices were similar enough to confuse one for the other, which is what happened to Yitzchak. 1
Ohr ha'Chayim: The voice can change, due to the speaker or the hearer (he does not hear so well). Feeling the hair of the hands is a fully reliable sign.
Why did Yitzchak say that the hands are like those of Esav? He touched goat skin. Goat hair is very unlike human hair!
Seforno #1: After much work on it, the hair resembled human hair.
Seforno #2: Yitzchak's age may have dimmed his sense of touch, to the point that he could not tell the difference. 1
Why is the first "Kol" missing a 'Vav'?
The Rosh and Divrei Eliyahu: So that it can be read "ha'Kal... ," in which case it means that when the voice of Yaakov is lax, the hands of Esav are strong." 1
In other words, when the children of Yaakov are lax in the study of Torah and in Tefilah, that is when Esav is able to defeat them in battle.
QUESTIONS ON RASHI
Rashi writes: "'The voice of Yaakov' - He spoke politely (lit. beseechingly), 'Please arise... '" Why not explain simply, that Yaakov's voice was different than Esav's?
Rashi writes: "'The voice of Yaakov' - He spoke politely." According to Rashi, why does Yitzchak refer here to Yaakov's politeness, and not to his use of HaSh-m's Name, which had alerted Yitzchak in the first place that it might be Yaakov (see Rashi to 27:21)?
Gur Aryeh: There were two factors that indicated that it was Esav - a) one does not lie to his father regarding something that will be discovered, b) his hands were hairy. But there were also two indicators that it was Yaakov - c) he used HaSh-m's Name, d) he spoke beseechingly. Factors a) and c) cancel each other out; they are usually, but not always, the case. That leaves factor d) - '"ha'Kol Kol Yaakov" to speak beseechingly; and factor b) - "ha'Yadayim Yedei Esav," i.e. hairy. Even someone who always speaks brashly might possibly change and speak politely, whereas one cannot change one's hands at all. Therefore, Yitzchak decided it was Esav, and gave a blessing. 1
Rashi writes: "'The voice of Yaakov' - He spoke politely." And did Esav not? We know that Yitzchak assumed Esav to be worthy!
Gur Aryeh: Yitzchak reasoned that Yaakov spoke in the manner of a poor man, whereas Esav spoke brusquely like a rich man (see Mishlei 18:23). This indicated to him that Esav would be an officer or lord, and that he ought to be blessed.