1 Nephi 20:4

And I did it because I knew that thou art obstinate,

and thy neck is an iron sinew, and thy brow brass;

and thy neck is an iron sinew, and thy brow brass;

is - 8 occurrences in 7 verses - 1 Nephi 20:2, 4, 22,   21:4, 6, 7, 20