I would posit an essential distinction between (a) outside reference books whose purpose is to provide us tools with which we can read languages foreign to us and (b) outside interpretation books that merely provide opinionated commentary on Scripture, no matter how erudite the author. Given that Scripture has been translated from its original languages, we need reference tools to help us discover what God originally intended to say versus what some human beings along the way wanted us to think He had said. However, while historical context is indeed interesting and often illuminating, when it is essential to our understanding, I believe the Author of it all already included it in the text; if it's not there, I believe it's appropriate to consider its absence to indicate that it's superfluous. The most sure path to hearing the Voice of God is to get as close as possible to reading the original manuscripts. Those mentioned reference tools can help us approximate that, but that is as close as we can get in this life, given that He has chosen to allow His Word to be polluted.
We do our best to hear Him, and sometimes we have to rely more on our heart than on our eyes.
We do our best to hear Him, and sometimes we have to rely more on our heart than on our eyes.