Which command must be configured on both spokes so two spokes can send traffic directly to each other (bypass the hub)?

The ip nhrp shortcut command is essential for enabling spoke-to-spoke direct communication in a DMVPN Phase 2 or Phase 3 network. When a spoke receives a packet from another spoke that it would normally forward via the hub, this command tells the spoke to initiate a direct NHRP resolution for the source of that packet. This allows the two spokes to establish a direct tunnel between them, bypassing the hub for subsequent traffic. Without this command, spokes would always send traffic destined for other spokes through the hub, even if a direct tunnel could be formed. ip nhrp nhs multicast is used on spokes to register for multicast traffic from the hub. ip nhrp map dynamic is a command used on the hub to allow dynamic NHRP mappings. ip nhrp redirect is a hub-side command that informs a spoke to initiate a direct tunnel to another spoke.