Why is one who slackens in his work a brother of the destroyer?
Rashi: A Chacham who separates from Torah, he is a brother to the Satan.
R. Yonah #1: This rebukes an Atzel who slackens in his work. Do not say that there is punishment only for slackening in others' work, but if I slacken in my own work, this is not a sin. The verse refutes this. It considers one who damages his own money a sinner - "Lo Sashchis Es Etzah" (Devarim 20:19), like Chazal said (Bava Kama 91b). One who slackens in his work and loses profit and wastes much good, he is a brother to the destroyer, for he is considered to damage his own money. Mashchis is a noun, like "v'Ish Kli Mashcheso b'Yado" (Yechezkel 9:1). This is put next to a Nirgan (8), for they are things that people think that there is no sin in them.
R. Yonah #2: This refers to one who slackens in Chachmah and Avodah. He destroys his days and years. He is no less [guilty] than one who destroys property. In many places, this Sefer scorns laziness about Chachmah and fear.
Mesilas Yesharim (Perek 6): Even though he does not do evil with his hands, do not think that he is far from it. He is his brother, and has the same Mazal.
Malbim #1: One who must work for the kingdom, and one built a building and destroyed it, and one sat and did not build at all - their punishments are the same. Either way, the building that they needed to build was not built. The one who slackened and did not do, he is the brother of, and resembles, the one who built and destroyed. Similarly, there is no difference between one who did a Mitzvah and an Aveirah that extinguishes the Mitzvah, and one who sits and does not do a Mitzvah or Aveirah. Both did not do what was incumbent on them.
Malbim #2: This refers to "Migdol Oz Shem Hashem" (10). Hashem's name is the tower that people build. This task is incumbent on them, to aggrandize His name and build His Mikdash. Some build and destroy, and some do not build at all. Their punishments are equal. This is also an answer to Tzadik v'Ra Lo mentioned above (17:26).
What does "Gam" come to include?
R. Yonah #1: This is the intent to slacken in his work. He thinks that there is sin only if someone hired slackens in what the employer hired him to do.
R. Yonah #2: This refers to slackening in work for a Nirgan. He says in his heart, if I will be diligent in my work, he will complain about me, just like if I slacken in it. Also he is a brother of the destroyer - he should not forfeit his faithfulness due to the bad Musar of the Nirgan!
