'Why does the Torah add "be'Yad Chazakah"?
Rashi: In reply to Yisrael's reference to Yitzchak's promise "ha'Kol Kol Ya'akov", they reminded them of his promise to him "ve'Al Charb'cha Tichyeh" and came to meet them with swords drawn. 1
Refer to 20:16:1:1. Even though Yisrael had preempted this by pointing out that "ha'Yadayim Y'dei Eisav" was not currently applicable (refer to 20:16:1:1 2
) we can say (be'Derech Melitzah - satirically) that Edom did not Darshen Chaseros vi'Yeseiros' - They did not Darshen missing letters and extra ones, or that they follow the Mikra (the way the word is pronounced) and not after the Mesores (the way it is written).
Seeing as Edom had no intention of attacking Yisrael, only to prevent them from passing through their land, and having already stated "Pen ba'Cherev Eitzei Likrasecha", why did they now go to meet thm with a large army?
Oznayim la'Torah: Because (seeing as Yisrael persisted in their request even after the first warning) that they did not take them seriously, so to demonstrate that they meant what they said, they marched towards them with an army - as a warning that they would attack them should Yisrael attempt to pass throught their land.
In Pasuk 18, the Torah writes "Lo Sa'avor Bi." Why is the word "Bi' omitted here?
Riva (on Pasuk 18): Initially, Yisrael asked to go through cities, intercity roads and vineyard, so they replied "you will not pass through me (wherever I live)." After, they asked to go only on roads, therefore it does not say "Bi".
