What is the meaning of "Domu"?
Rashi: Wait. This is like "Shemesh b'Giv'on Dom" (Yehoshua 10:12) and "Dom la'Shem" (Tehilim 37:7).
Why did Yonason make his action contingent on their response?
Rashi (9,10): If they say 'wait for us to come to you', this shows that they are succeeding now and their heart is high. If they say 'come upon us', this shows that Hashem put fear in their hearts; they fear to leave their place.
Radak: Words that a person hears are a sign of success. 1
Malbim citing Mahari: The Pelishtim could have said unlike either possibility that Yonason said, or they would come to fight them without saying anything. If they say like one of the two 'options', Hashgachah put the words in their mouths, to tell Yonason and his youth what to do. This is a level of Ru'ach ha'Kodesh, like Hashem told Gid'on (Shoftim 7:11) "you will hear what they speak..."
Radak: Hashem told Gid'on (Shoftim 7:11) "you will hear what they speak, and then your hands will be strengthened"!
Rav (Chulin 95b) says that any Nichush unlike that of Eliezer Eved Avraham and Yonason, is not Nichush. Nichush is forbidden!
Ra'avad (Hilchos Avodah Zarah 11:4): Rav means that any Nichush unlike that of Eliezer and Yonason, it is not proper to rely on it. Radak - i.e. if he did not stipulate about the Siman from the beginning. Do not heed those (e.g. the Rambam) who explain 'it is forbidden Nichush.' If so, Hashem would not have helped him [miraculously]! Rather, words that a person hears are a sign of success. Refer to 14:9:2:2*. Forbidden Nichush is superstitions based on weasels, birds, my bread fell from my mouth, it is morning or Rosh Chodesh?. Rav himself said 'if the ferry comes to me, I will have a good day; Shmuel would check via (from a verse he came to in) a Sefer, and R. Yochanan would ask a child 'what verse are you learning?' (95b) 1
Ran (95b, cited in Kesef Mishneh Hilchos Avodah Zarah 11:4): Nichush is forbidden when it is illogical to attribute the outcome to the Siman, e.g. his bread fell from his hand, or a deer crossed his path. This is Darchei ha'Emori! Eliezer and Yonason gave relevant Simanim. A girl proper for Yitzchak should have superlative Midos, and want to give also to the camels. If the Pelishtim say 'come to us', this shows that they fear an ambush. Two or three courageous people can often make many fearful people flee. Rav means that illogical Nichush is forbidden only if he acts on it, like Eliezer and Yonason [acted based on their logical Nichush]. One may make it a Siman, and join it with other reasons to act or refrain.
Kesef Mishneh (Hilchos Avodah Zarah 11:4) #1: The Rambam mentioned only Eliezer; he permits Nichush for Bnei Noach. Perhaps his text did not mention Yonason.
Kesef Mishneh (11:4) #2: Rav means that it is forbidden only if he acts on it, like Eliezer [who gave the rings before asking her father's name] and Yonason [who went to fight]. The Rambam omitted Yonason, for he would have fought in any case. He merely made a Siman to encourage his youth.
Radak: Nichush does not apply to [building] a house, [birth of] child or [marrying a] wife, but Siman applies (95b). I.e. one may not rely on it like a Nichush, but it is a Siman. If good came after one of these, he may rejoice [due to the Siman]; if bad came, he should worry and pray for mercy. It is a proper Siman if he stipulated from the beginning; if he did not stipulate, it is a proper Siman after three times.
