Rav Sadya Gaon: He will weary. Rashi - this is like "b'Itzavon Tochalenah" (Bereishis 3:17). Every man, his sadness is according to his work. Also one who does evil, he will reap according to what he seeds.

Torah Temimah citing Bava Basra 145b: This refers to one who learns only Mishnah. (He toils without benefit, for he cannot give rulings. One who learns Gemara can give rulings.

Rashi: One who quarries rocks from their source in the mountain, he wearies.

Rashbam: Like the previous verse, this warns against certain jobs, lest he stumble in them. One should not move big rocks, lest he have Itzavon ¹ . This is like "va'Yasi'u Avanim Gedolos" (Melachim I, 5:31).

Ri Kara: Sometimes moving rocks brings sorrow to him - "v'Golel Even Elav Tashuv" (Mishlei 26:27).

Rid: One's punishment is according to his deeds.

Seforno: Sometimes one moves rocks to a place improper for them, and he himself stumbles in them.

Metzudas David: He uproots and moves them to put them in a place where people will stumble on them. He himself is saddened, for he stumbles on them!

Rav Sadya Gaon: He will be damaged.

Rashi: It is an expression of heating, like "va'Tehi Lo Sochenes ¹ " (Melachim I, 1:2).

Ibn Ezra, Rid, Metzudas David: It is an expression of Sakanah (danger). Ri Kara - sometimes one chops wood, and a chip comes off the log and strikes and kills him.

Torah Temimah citing Bava Basra 145b: This refers to one who learns Gemara. (He is warmed (benefits from) his learning, for he can give rulings.)

Rashi: One who engages in Torah and Mitzvos, in the end he will benefit from them.

Ibn Ezra: This and the coming verse discuss the praise of Chachmah. Our verse is tied also to the previous verse. A Kesil breaches a fence, and a Chacham guards from this. There is nothing in the world that a person can get without fatigue, toil and danger. Even rocks, which are not in man's Reshus, one who wants to take them will be wearied taking them to where he wants. Also trees of the forest, it is weary to cut them and sometimes he is endangered.

Rashbam: One should not chop trees, due to great toil, and he is heated greatly. Similarly, one who does evil will eat the fruits of his deeds. One who seeds Amel, he will reap Aven.

Rid: This repeats "Masi'a Avanim Ye'atzev Bahem" (one's punishment is according to his deeds).

Seforno: Sometimes one chops wood in order to warm himself through them. Even though it is for a good purpose, sometimes evil results from it.

Metzudas David: He chops wood in order to throw it at people to kill them. He himself is endangered, for they fall on him. The matter is repeated to teach that it happens every time.