Saint Macarios the Great
The five wise virgins, watchful and alert, had taken oil in the vessels of their heart. That oil, not part of their own nature, means the grace of the Spirit. They were enabled to enter with the Bridegroom into the heavenly bridal chamber.
The other five virgins, however, were content with their own nature. They neither watched nor busied themselves to receive the oil of gladness [Ps. 44:6] in their vessels, while they were yet in the flesh. Instead, they sank into sleep through carelessness, slackness, idleness, and ignorance, or even fancied righteousness. Hence, they were shut out of the bridal chamber of the Kingdom, unable to give satisfaction to the heavenly Bridegroom. Held fast by their tie to the world, and by some earthly affection, they did not give their whole love or passionate devotion to the heavenly Bridegroom; thus they were not provided with oil.