This is the one who was mentioned by the prophet Isaiah when he said,

“The voice of one shouting in the wilderness,
‘Prepare the road for the Lord,
Make His highways straight (level, direct)!’”

This was to fulfill what was spoken by the prophet Isaiah:

so that He fulfilled what was spoken by the prophet Isaiah: “He Himself took our infirmities [upon Himself] and carried away our diseases.”

This was to fulfill what was spoken by the prophet Isaiah:

In them the prophecy of Isaiah is being fulfilled, which says,

‘You will hear and keep on hearing, but never understand;
And you will look and keep on looking, but never comprehend;

You hypocrites (play-actors, pretenders), rightly did Isaiah prophesy of you when he said,