Matthew 17:13

Then the disciples understood that he spake unto them of John the Baptist.
— Matthew 17:13, King James Version

In other translations

World English Bible (WEB)

Then the disciples understood that he spoke to them of John the Baptizer.

American Standard Version (ASV)

Then understood the disciples that he spake unto them of John the Baptist.

Young's Literal Translation (YLT)

Then understood the disciples that concerning John the Baptist he spake to them.