Matthew 11:9 calls John 'more than a prophet' — immediately preceding and setting up this identification as Elijah.

Matthew 17:10-13 explicitly confirms that John the Baptist is the Elijah who was to come, directly parallel to this verse.

Matthew 17:13 records the disciples' realization that Jesus meant John the Baptist as Elijah — confirming this identification.

Malachi 4:5 prophesies Elijah's coming before the Day of the Lord — this is the prophecy John fulfills as Elijah.

Mark 9:11-13 has Jesus affirm that Elijah has come in John the Baptist, parallel to this identification.

Luke 1:17 describes John going before the Lord in the spirit and power of Elijah, directly supporting John's identity as the promised Elijah.

John 1:21-23 records John denying he is Elijah — contrasting Jesus' affirmation here that John is Elijah in a prophetic sense.

Mark 9:13 gives the parallel account: Jesus says Elijah has come, referring to John — confirming the same teaching.