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"Pay attention to what I am about to tell you"

I will keep nothing back from you

The phrase "keep nothing back from you" is an idiom that means to tell someone everything. This can be stated in positive form. AT: "I will tell you everything the Lord tells me" (See: rc://en/ta/man/translate/figs-idiom and rc://en/ta/man/translate/figs-activepassive)