Lift not up your horn on high; a metaphor from untamed and stiff-necked oxen, which will not bow their heads to receive the yoke, but lift up their heads and horns to avoid it. Or, against the High, i.e. against God, who is mentioned under this same title, Psalms 56:2, though there it be rendered Most High. Speak not, to wit, against me and my government. With a stiff neck; with pride and contempt of my person, and with rebellion against God's will declared concerning my advancement, of which you are not ignorant. See 2 Samuel 3:17,18.
Related Commentaries of Psalms 75:5
Psalms 75:5
5 Lift not up your horn on high: speak not with a stiff neck.