Sometimes we see a picture of Lord Siva engaged in meditation. This verse (SB 5.17.16) explains that Lord Siva is always meditating upon Lord Sankarsana in trance. Lord Siva is in charge of the destruction of the material world

Expressions researched:
"Sometimes we see a picture of Lord Śiva engaged in meditation. This verse explains that Lord Śiva is always meditating upon Lord Saṅkarṣaṇa in trance. Lord Śiva is in charge of the destruction of the material world"

Srimad-Bhagavatam

SB Canto 5

Sometimes we see a picture of Lord Śiva engaged in meditation. This verse explains that Lord Śiva is always meditating upon Lord Saṅkarṣaṇa in trance. Lord Śiva is in charge of the destruction of the material world. Lord Brahmā creates the material world, Lord Viṣṇu maintains it, and Lord Śiva destroys it. Because destruction is in the mode of ignorance, Lord Śiva and his worshipable Deity, Saṅkarṣaṇa, are technically called tāmasī. Lord Śiva is the incarnation of tamo-guṇa.

SB 5.17.16, Translation and Purport

In Ilāvṛta-varṣa, Lord Śiva is always encircled by ten billion maidservants of goddess Durgā, who minister to him. The quadruple expansion of the Supreme Lord is composed of Vāsudeva, Pradyumna, Aniruddha and Saṅkarṣaṇa. Saṅkarṣaṇa, the fourth expansion, is certainly transcendental, but because his activities of destruction in the material world are in the mode of ignorance, He is known as tāmasī, the Lord's form in the mode of ignorance. Lord Śiva knows that Saṅkarṣaṇa is the original cause of his own existence, and thus he always meditates upon Him in trance by chanting the following mantra.

Sometimes we see a picture of Lord Śiva engaged in meditation. This verse explains that Lord Śiva is always meditating upon Lord Saṅkarṣaṇa in trance. Lord Śiva is in charge of the destruction of the material world. Lord Brahmā creates the material world, Lord Viṣṇu maintains it, and Lord Śiva destroys it. Because destruction is in the mode of ignorance, Lord Śiva and his worshipable Deity, Saṅkarṣaṇa, are technically called tāmasī. Lord Śiva is the incarnation of tamo-guṇa. Since both Lord Śiva and Saṅkarṣaṇa are always enlightened and situated in the transcendental position, they have nothing to do with the modes of material nature—goodness, passion and ignorance—but because their activities involve them with the mode of ignorance, they are sometimes called tāmasī.