Verses with the word stiff in the Old Testament (3 verses):

Deuteronomy 31:27
For I know thy rebellion, and thy stiff neck: behold, while I am yet alive with you this day, ye have been rebellious against the LORD; and how much more after my death?

Psalms 75:5
Lift not up your horn on high: speak not with a stiff neck.

Jeremiah 17:23
But they obeyed not, neither inclined their ear, but made their neck stiff, that they might not hear, nor receive instruction.