Gregory the Dialogist

Till He fill thy mouth with laughing, and thy lips with shouting. For the 'mouth' of the righteous will then be 'filled with laughing' when the tears of their pilgrimage being done, their hearts shall be filled to the full with exulting in eternal joy. Concerning this laughing 'Truth' saith to His disciples, Verily, verily, I say unto you, that ye shall weep and lament, but the world shall rejoice; and ye shall be sorrowful, but your sorrow shall be turned into joy. …

Morals on the Book of Job, Book VIII ↗

Thomas Aquinas

Yet Job could say, "Whatever you may say and you want to prove with analogies I have experienced the contrary. For when I was simple, I suffered adversity and my evil adversaries prevailed against me." Bildad wishes to disprove this saying, "Until your mouth be filled with laughter and from your lips break forth a cry of joy," as if to say: What I have told you is so true that you will experience it, in yourself, but only if you will be simple in such a way that your happiness which will follow from your prosperity will be …

Commentary on Job ↗