Numbers 14:16
Because the Lord was not able to bring this people into the land which he sware unto them, therefore he hath slain them in the wilderness.
Cross-references
Deuteronomy 9:28 repeats the exact same hypothetical complaint from the nations about God's inability to bring Israel to the land.
Deuteronomy 32:27 shows God fearing enemy misinterpretation — the exact same rationale for sparing Israel.
In Psalm 115:2, the nations' taunt 'Where is their God?' mirrors the mockery feared in Numbers.
Jeremiah 14:9 echoes the same doubt: the people ask why God is like a mighty man who cannot save, paralleling the nations' accusation that God could not bring Israel into the land.
Jeremiah 32:22 affirms God actually gave the land He swore, directly refuting the nations' accusation in Numbers 14:16 that He could not.
In Joshua 7:9, Joshua uses the same argument about God's reputation among nations to avert defeat.
Isaiah 48:11 declares God acts for His own name's sake — the motivation Moses appeals to in Numbers.
In Ezekiel 36:20, the nations again question God's ability, saying His people left His land — similar to the accusation that He couldn't bring them in.