Matthew 3:11 records John's own words about Jesus being mightier, illustrating why the least in the kingdom is greater than John.

Matthew 5:19 also uses 'least in the kingdom of heaven' but in the context of obeying commands, not comparing to John.

Luke 1:15 describes John's greatness from birth and being filled with the Spirit, supporting Jesus' statement that no one born of woman is greater.

Luke 7:28 is a parallel passage with almost identical wording about John's greatness and the least in the kingdom.

Luke 9:48 teaches that the least among you is the greatest, directly parallel to the least being greater than John.

John 1:15 records John's testimony that Jesus surpasses him, aligning with Jesus' statement that the least in kingdom is greater than John.

John 1:27 has John saying he is unworthy to untie Jesus' sandals, reinforcing the theme of relative greatness.

Malachi 3:1 is the prophecy identifying John as the messenger who prepares the way — the role that makes him greatest among the born of women.