Gregory the Dialogist

Because therefore I have waited, and they have not spoken, they have stood, and have answered no more. Wise men are accustomed to make it the limit of their speaking, to speak so far as to silence their adversaries. For they wish not to display their own powers, but to put down the teachers of heresy. But after it is said of the friends of Job, They were afraid, they answered no more, they removed speech from themselves, Eliu subjoins and says, I have waited, and they have not spoken; they have stood, and have answered no more. …

Morals on the Book of Job, Book XXIII ↗

Thomas Aquinas

Since, therefore, they had failed, he says that he wants to make up for their defect, and so he says, "Therefore, as I waited," for a long time in deferring to them, "and as they did not speak," in answer to the discourses of Job, "I will answer for my part," because the defense of the truth is everyone's task, and each one should devote to it what he can as though from his part. However, he was not moved only by the zeal to defend the truth, but also by vainglory, and so he says, "and I will show my knowledge."

Commentary on Job ↗