Proverbs 15:3
"The eyes of the LORD are in every place, keeping watch on those who are evil and those who are good." Proverbs 15v3 (NET)
Observations
This proverb wonderfully contrasts the dread and hope God inspires through the same attribute.
The LORD is aware of all things, there is nowhere to go to escape from him. The LORD is not simply aware in a dispassionate sense, like some bored divine uncle, waiting for the kids to go to bed so he can have an adult conversation. Rather, he is "keeping watch". For the evil doer, this is terrifying. His watch is like the penetrating gaze of a musical examiner, recording every slip and mistake. Many athiest have complained about God's watchful eye, revealing discomfort in what they have done and what they want to do. The dread inflicted on us when we hear "God is watching" is a clear sign of a guilty conscience. Don't be fooled by those who complain about God's "watching", as if this were simply a violation of their privacy -- this is the cry of a guilty conscience. The LORD is keeping watch on all evil, and, given he does not wink at evil, he will bring evey evil dead to justice.
The LORD also keeps watch on the good; another reminder of God's justice, but this time from the other end. He "keeps watch", not to keep an account, but to care. His watch is like a young mother at the park ensuring thier toddler is safe, happy and clean. This watching is a great comfort to the "good", that is, those who have had their sins forgiven and live with Jesus Christ as their king. Whatever hardship, injustice or inner sadness that the believer experiences, God sees; more than that, he is keeping watch.
Christ
Christ knew the hearts of those around him, the gospels record his incredible powers of perception. When we read this sections, it is too easy to simply credit this to his divinity (of course he knew what was in people's hearts, he is God). This truncated reasoning skips over the nature of God revealed in Christ. How did he know what was in people's hearts? He was keeping watch. Jesus was an expert, intuitive people watcher. Most of us are too distracted by ourselves to properly observe those around us. Not so with Jesus. He knew the Scriptures and he kept watch on those around him, this is how he was able to know what was in people's hearts.
Application
There are two prongs of application here. One is inward and receptive, one is outward and active. Read the proverb again and monitor your heart. Are you comforted or terrified by God's watch keeping: this will reveal you heart's condition before him. Are you terrified? Repent and believe in Jesus. Are you comforted? Rejoice in what you have in Jesus. Secondly, as those made in God's image and remade in Christ's, watch those around you. Watch the evil, to catch them and bring God's light to shine on their deeds (this is a subtle and nuanced task, best done in community). Watch the good, to delight in what God is doing in them and to comfort them.