This passage is the heart of Nephi’s message. He reminds his brothers that Moses drew life-giving water from the rock. The brothers cannot deny this. They must admit that a prophet led Israel and that Yahweh manifested his power through that prophet.
Verse 30 closes the logical trap on Laman and Lemuel. Just as the children of Israel murmured against their prophet and leader, so Laman and Lemuel have complained and resisted the leader on whom Yahweh’s mantle rests. They cannot deny their national history nor the allusion to their own situation. Yet this condemnation contains hope along with accusation. The children of Israel murmured, but they also repented. Nephi holds out the same hope to Laman and Lemuel that all will be well if they repent. Nephi is not condemning his brothers outright but calling them to repentance.