John Gill Commentary Job 40:10

"Deck thyself now with excellency and dignity; And array thyself with honor and majesty." — Job 40:10 (ASV)

Deck thyself now [with] majesty and excellency
With excellent majesty, as I am decked and clothed, (Psalms 93:1) ;

and array thyself with glory and beauty ;
appear in the most glorious and splendid manner you can, make the best figure you are able, put on royal robes, and take your seat and throne, and sit as a king or judge in state and pomp, and exert yourself to do the following things;

or take my seat and throne as the judge of the whole earth, and try if you can govern the world better than I do; for these and the expressions following are said in an ironic manner.