Verses with the word chiefest in the New Testament (3 verses):

Mark 10:44
And whosoever of you will be the chiefest, shall be servant of all.

2 Corinthians 11:5
For I suppose I was not a whit behind the very chiefest apostles.

2 Corinthians 12:11
I am become a fool in glorying; ye have compelled me: for I ought to have been commended of you: for in nothing am I behind the very chiefest apostles, though I be nothing.