The behavior of the Israelites in the wilderness stood in stark contrast to the salvation God had just provided for them. Rather than trusting Him, they chose to rebel and refuse His instructions. The historical focus falls directly on the ancestors of the nation, specifically the generation of the spies and the people who stood with them [רלב״ג]. Emphasizing their identity as the fathers of the nation serves to highlight the weight of their actions [מצודת דוד], [ביאור שטיינזלץ]. They acted with intentional wickedness [ביאור שטיינזלץ], a deliberate defiance that first took root when they demanded to send men to scout the land before entering it [מלבי״ם].
This intentional sin led to a profound stubbornness, described through the vivid image of stiffening the back of the neck [מצודת ציון]. It operates as a metaphor for deep obstinacy [ביאור שטיינזלץ], painting a physical picture of a people whose necks became so rigid that they could no longer turn their faces to look toward God [מצודת דוד].
Driven by this intense stubbornness, they refused to listen to God's commandments. Moses attempted to encourage them, reminding the people that God would fight for them just as He had done in Egypt. However, they completely dismissed his words and ignored the miracles they had personally experienced. Their rebellion ultimately reached a point where they asked to appoint a new leader and return to Egypt [מלבי״ם, רלב״ג].