Why did he tell him to run to the youth?
Rashi: Do not go to measure more ? Hashem consulted with His entourage, and decided that there be no limit [to the size of Yerushalayim]. Run to tell Zecharyah!
Malbim: Inform the Navi that the wall will be temporary. This is not the true Ge'ulah. Refer to 2:8:4:3.
Why is he called a youth?
Radak #1: Perhaps he was young when he had Nevu'ah, like Shmuel and Yirmeyahu.
Radak #2: Zecharyah served an older Navi, therefore he is called Na'ar (in comparison), "Yehoshua bin Nun Na'ar" (Shemos 33:11).
Why did the latter angel send the first, and not tell Zecharyah by himself?
Radak: Since the first spoke to Zecharyah initially, he should tell him [that Hashem retracted]. Even though he saw the angel measure Yerushalayim, it will be Perazos (refer to 2:8:4:2). `
What is the meaning of "Perazos Teshev"?
Rashi: There will be no wall, in order that anyone who comes can settle in it. It will grow daily!
Radak: Many will dwell outside the wall, for the city cannot contain them, even though it will be much longer and wider than what it was. Arei 1 Perazos" are without a wall, doors and bolt.
Malbim: There will come a time, in the end of days, when the limited wall of Yerushalayim cannot contain the multitude of people and animals. The city will constantly expand!
If they are cities, they are not Yerushalayim! If the word Arei is not a mistake, perhaps Radak means 'Perazos are like "b'Arei ha'Perazos" (Esther 9:19), without a wall?' (PF)
