Gregory the Dialogist

All these things God worketh three times with every man. Of this man tempted and beaten by the scourge it had been said before, His bread becomes abominable to him in his life, and his soul hath drawn nigh to corruption, and his life to the destroyers. [ver. 22] But it was subsequently added, He shall pray unto God, and He will be favourable unto him, and he will see His face with joy; and he hath delivered his soul from going onward to destruction, but that it should live, and behold the light. [ver. …

Morals on the Book of Job, Book XXIV ↗

Thomas Aquinas

Because God does not immediately and finally damn man, but warns him many times, Eliud adds, "Behold, all these things," the instruction through dreams and rebuke through pains and healing, "God works in three ways," i.e. many times for as long as he thinks them useful. But he uses the number three to conform to human usage in which men are usually warned or summoned three times. God does this not only for one, but for all those in need of it, and so he says, "for each one," whom he sees must be instructed and chided.

Commentary on Job ↗