Isaiah 40:3-5 expands the quote Mark uses — adding the command to make straight paths and the promise that God's glory will be revealed.

Matthew 3:3 independently applies the same Isaiah 40:3 prophecy to John, reinforcing his identity as the wilderness voice.

Luke 3:4-6 quotes Isaiah 40:3-5 in full, providing the broader context of preparing the way for the Lord's salvation.

In John 1:19-23, John explicitly identifies himself as the voice crying in the wilderness from Isaiah 40:3, confirming the prophecy.

In Malachi 3:1, the promised messenger who prepares the way is the same figure as the voice in the wilderness—John the Baptist.

In Luke 1:76, Zechariah prophesies that John will 'go before the Lord to prepare his ways,' directly mirroring the Isaiah quote.

In Luke 3:2, the word of God comes to John in the wilderness, where he begins his ministry as the voice preparing the way.

In John 1:23, John the Baptist directly quotes the same Isaiah passage, explicitly identifying himself as the voice in the wilderness.

In Acts 18:25, Apollos knew only John's baptism — the same preparatory repentance heralded by the voice.

In John 1:31, John explains his baptism was to reveal Jesus, which is the purpose behind preparing the way.