According to the apostle Paul, the human being possesses “eyes of the heart.” (Ephesians 1:18) I assume that this expression was coined to express the fact that a believer has the capacity to see things in the spiritual realm which cannot be seen with physical eyesight.
In a similar way, people have “ears of the heart.” In the great vision Isaiah had of the Lord on His throne, we can see an example of spiritual eyes and ears. He said to the prophet, “Go, and tell this people: Keep on listening, but do not perceive; keep on looking, but do not understand. Render the hearts of this people insensitive, their ears dull, and their eyes dim, otherwise they might see with their eyes, hear with their ears, understand with their hearts, and return and be healed.” (Isaiah 6:9-10) It isn’t a person’s physical eyes and ears that can perceive the things of the spiritual realm but the heart.
In one of His discourses, Jesus referred to Himself as the shepherd of His people, and said that “the sheep hear his voice, and he calls his own sheep by name and leads them out.” (John 10:3) He is clearly referring to the call to follow Him. Here, too, we see an example of those who have spiritual ears.
In our subject verse above, David claims that his heart has heard the Lord calling to him. His answer is that he hears the call and is responding to it. Seeking the Lord is one of the great principles of the Christian faith. Believers should do their utmost to strive to press in spiritually: to ask for, to plead for, even to beg for the presence of God. This should be an ongoing discipline of the Christian life and yet there are certain occasions when the Lord makes His follower to know that he would be richly blessed if he would seek His face right now.
There is a Greek term (kairos) that is sometimes translated as “time,” while on other occasions the word “opportunity” is the chosen English word. The spiritual meaning of this term is that there are certain occasions in life when a spiritual opportunity presents itself and it is wise to take advantage of it. I believe that is the sense of what is being expressed in Psalm 27:8.
The Lord has moved near to David, is calling him to seek His face, to press into His presence. The poet/king understands that this is one of those precious moments when he can derive much good for his soul if he will take advantage of the opportunity.