make every effort to enter: If we do not actively obey God's voice and respond to the good news (Hebrews 4:1–2), we will face consequences like the wilderness wanderers did. We will fall.
us … no one: Obedience is not just a personal issue. God's people have a shared responsibility to obey and should support each other in this effort (compare 3:13; 10:25; 12:15).