Then the disciples understood that He spoke to them of John the Baptist.
Matthew 17:13
Surrounding context
17:12 But I say to you that Elijah has come already, and they did not know him but did to him whatever they wished. Likewise the Son of Man is also about to suffer at their hands."
17:13 Then the disciples understood that He spoke to them of John the Baptist.
17:14 And when they had come to the multitude, a man came to Him, kneeling down to Him and saying,