How to Separate Bible Study and Devotional Reading

I was told that studying the Bible for sermons was not an equivalent to devotional time in the Word of God.

I am not in complete disagreement with this thought. However, I have failed to find this clear distinction within the Instruction of Scripture.

The inspiration for a sermon should begin in personal reading. Furthermore, the preacher should be personally invested into his sermon, both in preparation and delivery.

Therefore, a minister should not divide his reading. What strength is in a sermon without devotion? What use is devotional reading without the elements of persuasion and practical application?