Which Divrei Chachamim are discussed?
Rashi: Chachamim made fences to guard people from sin, e.g. Kodshim that the Torah permits eating them until dawn. Chachamim said, until midnight. The same applies to the night Keri'as Shma.
What are "Darbonos"?
Metzudas Tziyon: It is like a needle at the end of the plowshare used to make the animal plow straight - "Lehatziv ha'Darban" (Shmuel I, 13:21).
How are Divrei Chachamim like Darbonos and nails?
Rashi citing Chagigah 3b: A Darban makes cattle go straight 1 when plowing, in order to bring [grain, which enables] life to the world. Also Divrei Torah direct those who learn it to go from ways of death to ways of life. Do not say that Divrei Torah are Metaltelim (moveable), just like a Darban - they are fixed like nails!
Ibn Ezra: Some words of early [Chachamim] are like Darbonos for animals - they afflict them, and make the Nefesh wise. Some are like big nails that gather the doors, lest they separate. "Zos Toras ha'Adam" (Shmuel II, 7:19; this is what is proper for man - Radak there).
Rashbam: It is a repetition to say that they are like nails inserted at the end of the stick.
Rid: Just like Darbanos makes animals go straight, Divrei Chachamim explain the Torah via traditions from Sinai, Gezeirah Shavah and Kal v'Chomer. Nails do not budge from their place; so one should not budge from Divrei Chachamim right or left.
Seforno: Divrei Chachamim straighten man, so their purpose is very important. However, it is difficult to understand them like removing a nail from where it was inserted. Therefore, [Shlomo] showed many ways to understand them.
Metzudas David: Just like Darbanos makes animals go straight, Divrei Chachamim straighten man to go in the ways of Chachmah.
Rashbam: So Divrei Torah teach one not to make his path crooked and ruin his ways.
Why is "Masmeros" written with a Sin?
Rashi, from Tanchuma Vayelech 1: This is like Mishmaros - the Torah has 24 Seforim [of Tanach 1 ], like the number of Mishmaros of Kehunah and Leviyah.
Trei Asar counts as one, and also Shmuel, Melachim, Divrei ha'Yamim and Ezra-Nechemyah count as one each. The division of the latter four into two Seforim each was via Nochrim. (PF)
Why does it say "Netu'im"?
Rashi citing Chagigah 3b: Just like a Neti'ah (sapling) multiplies and grows, also Divrei Torah 1 , to find reason in them.
Metzudas David: Their words last.
Mishnas R. Aharon 4, p.31: Investigation of what was given on Sinai, it widens Da'as and deepens understanding.
What are "Ba'alei Asufos"?
Torah Temimah citing Chagigah 3b: Ba'alei Asufos are Chachamim who sit in Asufos (gatherings) and engage in Torah.
Rav Sadya Gaon: They are inserted nails gathered and matching.
Rashi: They are nails with big heads at the Sof (end). Seforno - this enables one to remove them with tongs or another Kli. (Normally it is hard to remove them. Also Chachamim facilitate understanding what is normally hard to understand. - PF)
Ibn Ezra, Metzudas David: They gather from many Seforim and make compositions.
Rashbam: Ba'alei Asufos are Chachamim; people gather to hear their words.
Rid: They are Chachamim who gather, learn and debate, to explain the matter correctly.
Why does it say "Nitenu me'Ro'eh Echad"?
Chagigah 3b, partially brought in Rashi: Some Chachamim are Metamei and some are Metaher; some forbid and some permit; some disqualify and some are Machshir. If so, how can one learn? All of them "Nitenu me'Ro'eh Echad" - one Kel 1 gave them, one leader said them, from the Master of everything - "va'Ydaber Elokim Es Kol ha'Devarim ha'Eleh" (Shemos 20:1).
Seforno: Their words are included in the words of the shepherd (leader) of Yisrael.
Ibn Ezra, Metzudas David: It says "Ro'eh" (shepherd), for man was compared to an animal, which needs a Darban.
