Job 9:30

If I wash myself with snow water - Supposed to have a more detergent quality than common water; and it was certainly preferred to common water by the ancients. Of this we find an example in an elegant but licentious author: Tandem ergo discubuimus, pueris Alexandrinis Aquam in manus Nivatam infundentibus, aliisque insequentibus ad pedes - Petr. Satyr., cap. xxxi. "At length we sat down, and had snow water poured on our hands by lads of Alexandria," etc. Mr. Good supposes that there is an allusion here to the ancient rite of washing the hands in token of innocence. See Psalm 26:6 : I will Wash my hands in Innocency; and Psalm 73:13 : Verily I have cleansed my heart in vain, and Washed my Hands in Innocency. And by this ceremony Pilate declared himself innocent of the blood of Christ, Matthew 27:24.

If I wash myself with snow water - If I should make myself as pure as possible, and should become, in my view, perfectly holy. Snow water, it seems, was regarded as especially pure. The whiteness of snow itself perhaps suggested the idea that the water of melted snow was better than other for purification. Washing the hands formerly was an emblem of cleansing from guilt. Hence Pilate, when he gave up the Savior to death, took water and washed his hands before the multitude, and said that he was innocent of his blood; Matthew 27:24. The expression used here by Job, also is imitated by the Psalmist, to denote his innocence:

I will wash mine hands in innocency:

So will I compass thine altar, O Lord. Psalm 26:6.

Verily I have cleansed my heart in vain,

And washed my hands in innocency.

9:30 If - If I clear myself from all imputations, and fully prove my innocency before men.