John Gill Commentary Job 21:3

"Suffer me, and I also will speak; And after that I have spoken, mock on." — Job 21:3 (ASV)

Suffer me that I may speak
To go on with his discourse, without any interruption, until he had finished it; as he before craves their attention, here he entreats their patience to hear him out, as well as to give him leave to begin; they might by their gestures seem as if they were breaking up and departing; or they raised a tumultuous clamour, to hinder his proceeding to reply; or he might fear, that if he was allowed to speak, they would break in upon him before he had done, as they had already; or "bear me", as several of the Jewish commentators explain the phrase; though what he was going to say might sit heavy upon their minds, and be very burdensome, grating, and uneasy to them; yet he entreats they would endure it patiently, until he had made an end of speaking:

and after that I have spoken, mock on ;
as they had already, (Job 12:4) (17:2) ; they had mocked not at his troubles and afflictions, but at his words and arguments in vindication of his innocence; and now all he entreats of them is, that they would admit him to speak once more, and to finish his discourse; and then if they thought fit, or if they could, to go on with their scoffs and derisions of him; if he could but obtain this favour, he should be easy, he should not regard their mockings, but bear them patiently; and he seems to intimate, that he thought he should be able to say such things to them, that would spoil their mocking, and prevent it for the future; so the Greek version renders it, "you shall not laugh"; and the words being singular have led many to think, that Zophar, who spoke last, is particularly intended, though it may respect everyone of his friends.