What are "Semuchim"?
Brachos 10a: Our verse is the source 1 to expound the adjacency of verses.
Rashi (from Shir ha'Shirim Rabah 5:14): His commands have a strong support. Punishments and warnings strengthen them. The Parshiyos are arranged in order to expound (adjacencies) - "Shokav Amudei Shesh" (Shir ha'Shirim 5:15).
Malbim: Hashem's commands. They are the pillars that support the world.
Surely, there is a tradition for Sinai, and the verse is a mere Asmachta. We do not learn Torah laws from Nevi'im or Kesuvim! (PF)
Why does it say "Asuyim be'Emes v'Yashar"?
Radak: Those who guard Hashem's laws and go in His will never stumble.
Malbim: This is why Hashem's commands are faithful, and the pillars on which the world stands - "Anochi Sikanti Amudeha" (75:4).
