What is the significance of the mountains ceasing and the hills faltering?
Rashi: Even if the merit of the Avos and Imahos will finish, "My Chesed will not depart from you."
Radak #1: Mountains and hills are the most enduring matters in the land, and even so, sometimes they cease and falter via an earthquake. My Chesed and Bris with you is more enduring - it will never cease.
Radak #2: It is a metaphor for Nochri officers.
Malbim: Not only is it harsh for Me to eradicate you, like it is harsh for Me to eradicate the entire world. Even if it could be imagined that the mountains would cease and I would wipe out the entire settlement on the land and nullify the Shevu'ah of the flood, Mash (ceasing) is with intent, and Mismotet (faltering) is due to weakness. If the big mountains will cease via intent, the small hills by them will falter due to weakness, when they have no support from the mountains. So the verse depicts Hashem's Chesed to the great mountains and the Bris of Shalom that He made with Yisrael to the hills supported via the mountains' strength. So this Bris of Shalom does not rely on Yisrael's merit, only on Hashem's Chesed. If Hashem's Chesed would cease, the Bris Shalom would falter, for it itself is weak. However, His Chesed will not cease, for it is constant; it does not change or depend on the nation's deeds and virtue. Therefore, also the Bris Shalom will not falter.
What is the significance of Hashem's Chesed ceasing and His Bris Shalom faltering?
Malbim: Refer to 54:10:1:4.
