Job 3:1 describes Job opening his mouth to curse — Elihu now opens his mouth to speak, a parallel action.

In Job 35:16, Elihu accuses Job of opening his mouth in vain — contrasting with his own sincere speech here.

In Job 34:3, Elihu continues the theme of testing words — a logical follow-up to his opening his mouth to speak.

Psalm 78:2 uses 'open my mouth' for teaching — Elihu adopts the same idiom for his speech.

In Matthew 5:2, Jesus also opens his mouth to teach — a parallel action of authoritative speech.

In 2 Corinthians 6:11, Paul speaks of an open mouth and heart — a parallel to Elihu's declaration of speaking sincerely.