by them = in them. Hebrew. bahem, as in Psa_19:4, going about the Scriptures, moving and dwelling in the written Word, as the sun does in the heavens. (Compare 1Ti_4:15; 1Ti_3:14.)
warned = enlightened; hence, taught or admonished.
keepings = observing, or watching; as observers watch the heavenly bodies. Compare Psa_130:6. Isa_21:11).