Matthew 3:1-3 sets John's ministry in the wilderness, confirming the location Jesus references as the place people went to see John.

Matthew 3:5 describes the crowds from Jerusalem and Judea going to John — the very people Jesus addresses in his question.

Matthew 21:25 has Jesus questioning religious leaders about John's authority, echoing his earlier rhetorical question about John's significance.

Mark 1:3-5 provides the parallel account of John's wilderness preaching and the crowds coming, grounding Jesus' question.

Luke 3:3-7 recounts John's preaching in the wilderness, confirming the setting and the crowds' response.

Luke 7:23 is the beatitude concluding John's inquiry; Matthew 11:7 then begins Jesus' discourse about John. They are sequential in Luke's parallel account.

John 5:35 calls John a burning and shining lamp, directly affirming Jesus' point that John was no weak reed.

Luke 1:80 describes John growing strong in spirit in the wilderness — directly connects to Jesus asking what they went to see in the wilderness.

Luke 3:2 places John in the wilderness receiving God's word — same wilderness setting as Jesus' question about John.