Isaac of Nineveh

Now if the good God sees that a man’s heart has not inclined to any of these things as David said, indicating the same, “You have tested my heart, You have visited it in the night, You have tried me by fire, and unrighteousness was not found in me,” then God will help him and deliver him. Why does he say “in the night” and not “in the day”? Because the enemy’s deceptions are a night, as Paul also said, “We are not children of the night but children of the day,” since the Son of God is the Day, but Satan is night.