Thought from Today's Old Testament Passage:
[2 Chron. 25] The story of the reign of Amaziah opens with a remarkable statement which gives us the key to all that follows. "He did that which was right in the eyes of the Lord, but not with a perfect heart." The general aim of the man was right, but execution was spoiled by imperfection. Nothing is wholly satisfactory to God save the perfect heart, because nothing else can possibly produce the best in man….
The root idea of the Hebrew word translated "perfect" is being whole, complete. Imperfection of heart consists in incomplete surrender. Some chamber of the temple is retained for selfish purposes. What it was in the case of Amaziah we are not told, but the fact remains, that notwithstanding the general direction of his life, either through personal indulgence, or ambition, or carelessness, the whole heart was not set on doing the will of God. One room possessed by the foe inside the fortress is ever the gravest peril. Sooner or later, almost inevitably, the man in that room opens the door for foes without. Thus it was in the case of Amaziah, and thus it is in the case of all who are not wholly devoted.
G. Campbell Morgan, An Exposition of the Whole Bible (Fleming H. Revell Company, 1959), pp. 179-180.