John Trapp on Job 38:23

Verſe 23. Which I have reſerved againſt the time of trouble] Or, Againſt the time of the enemy to puniſh him, as Exod. 9.24. Joſh. 10.11. Iſai. 30.30. By deep Snowes men are ſometimes withered and deſtroyed: by violent hail-ſtones and coales of fire (as Pſal. 18.13, 14, 15.) What an overthrow was procured againſt the Quades by the prayers of the thundring Legion, as they were afterwards called in the dayes of Aurelius the Emperour? Ingens grando compluraque fulmina in hoſtes ceciderunt; Dio in vit. &c. Ant. Phil. Huge hail-ſtones and many light-bolts fell upon the enemy ſaith the Heathen Hiſtorian.

Againſt the day of battle and war] When God is pleaſed to bring forth his upper and lower troops ready preſt, as the Rabbins phraſe it.