Though interpreters do greatly vary. in describing what is particularly meant here by
nitre and soap, and it would be superfluous to mention here; yet all agree they are some materials that artists make use of for the cleansing away spots from the skin, clothes, or other things; and the sense is plain, that the blot of his people is by no art to be taken out: it cannot be covered by excuses; Though thou wouldst dissemble thy idolatries, thou canst not deceive me: nor expiated by sacrifices; it is beyond the power of all superstitious or religious washings to cleanse away, which may be understood by these natural and artificial ways of cleansing.
Thine iniquity is marked: the meaning seems to be either, Thy filthiness is so foul that it leaves a brand behind it that cannot be hid or washed out, but will abide: see Jer_17:1. Or, according to another acceptation of the word,
it is laid up with God. See the like Deu_32:34Hos_13:12. Purge thee, wash thee, do what thou wilt, thou canst by no means conceal thy wickedness from me, Job_9:20. They that would see greater variety of interpretations, let them consult the Synopsis.