What is the meaning of "Lehashlich"?
Rav Sadya Gaon: To abandon.
Rashi: This refers to Bachurim of Yisrael who were cast - "Tishtapachnah Avnei Kodesh" (Eichah 4:1).
What is the connection of casting rocks and gathering them?
Rashi: [Bachurim of Yisrael were cast off]; they will be gathered from Galus - "v'Hoshi'am Hashem Elokeihem ba'Yom ha'Hu k'Tzon Amo Ki Avnei Nezer Misnosesos Al Admaso" (Zecharyah 9:16).
Ibn Ezra: Even if it occurred [that rocks pained him in his dwelling; Metzudas David - lest he be injured through them], he should cast them away. When he needs them [to build something], it is time to gather them.
Likutim on Koheles Rabah 3:7: War is a time to cast rocks; Shalom is a time to gather them 1 .
Shemos Rabah 46:2 #1: "Tishtapachnah Avnei Kodesh" (Eichah 4:1); "Bonei Yerushalayim Hashem" (Tehilim 147:2). Bava Kama 60b - Hashem said 'I lit the fire in Tziyon; I must pay for it. I will rebuild it with fire - "I will be like a wall of fire around (Yerushalayim)."'
Shemos Rabah 46:2 #2: Moshe broke the Luchos, therefore "Pesal Lecha" (Shemos 34:1) - he must make the latter Luchos. 2
Likutim: There is an omission in our texts of the Midrash so this was mistakenly expounded to say 'when your wife is Tehorah', and to gather rocks when she is Temei'ah (and so R. Avigdor brings). Refer to 3:5:3:2 and the note there.
Likutim on Koheles Rabah: In all of these times, the former causes the latter.
What are the times to embrace and distance from embracing?
Rashi: "Ka'asher Yidbak ha'Ezor Al Masnei Ish" (Yirmeyah 13:11; so Hashem embraced Beis Yisrael and Beis Yehudah). "V'Richek Hashem Es ha'Adam" (Yeshayah 6:12).
Ibn Ezra: Even desire in man's Ru'ach, there is time to embrace [his wife] who lies in his bosom, and a time to distance her. Likutim on Koheles Rabah 1 - embrace her when she is Tehorah, and distance from embracing her when she is Temei'ah.
Koheles Zuta: If you see a Kas 2 (group) of Tzadikim, embrace them; if you see a Kas of Resha'im, distance from embracing.
Metzudas David: There is a time to pursue love of someone and to embrace, and a time to distance, lest he come to embrace.
