You speak, he hears

As for visiting God's Messenger, on him be peace: you must stand before him in the manner we have described, visiting him in death as you would have visited him in life. Do not approach his tomb except as you would have approached his noble person if he had been alive. Just as you would have considered it respectful to refrain from touching or kissing his person, rather standing back and bowing before him, you should now act accordingly. Touching and kissing tombs is a custom of Christians and Jews. Realize that he is aware of your presence, of your standing there and of your visit; that he is receiving your greeting and benediction. Imagine his noble form as it lies in the tomb in front of you. Feel in your heart his tremendous dignity. For he is reported as saying that God, Exalted is He, has appointed to his tomb an angel who conveys to him the salutations of those members of his Community who salute him.

This refers to those who are not actually present, so how about those who leave home and cross desert wastes from longing to meet him, content merely to behold his noble shrine since they have no possibility of witnessing his noble countenance? He said, on him be peace: 'When someone blesses me once, God blesses him ten times.' This refers to the reward for oral benediction, so how about the reward for coming in person to visit him?

Next, you should go to the pulpit of God's Messenger, on him be peace, imagining you can see the Prophet, on him be peace, ascending it. Picture to yourself his radiant appearance, as if he were there on the pulpit, surrounded by the Emigrants and Helpers, may God be pleased with them, as he urges them in his sermon to be obedient to God, Great and Glorious is He. Ask God, Great and Glorious is He, not to part you from him at the Resurrection.

Imam al-Ghazali (Inner Dimensions of Islamic Worship).

Even Imam al-Nawawi, in his book Kitab al-Adhkar, had emphasized the benefits of visiting the Prophet's grave. It's too bad the book has been tampered with, and I'm not simply making this up.