Srimad-Bhagavatam: Canto 8 - Chapter 1 - Verse 22

Sanskrit:

त्वमेक: सर्वजगत ईश्वरो बन्धमोक्षयो: ।तं त्वामर्चन्ति कुशला: प्रपन्नार्तिहरं गुरुम् ॥ २२ ॥

ITRANS:

tvam ekaḥ sarva-jagataīśvaro bandha-mokṣayoḥtaṁ tvām arcanti kuśalāḥprapannārti-haraṁ gurum

Translation:

O lord, you are the cause of bondage and liberation of the entire universe because you are its ruler. Those who are advanced in spiritual consciousness surrender unto you, and therefore you are the cause of mitigating their distresses, and you are also the cause of their liberation. We therefore worship Your Lordship.

Purport:

Actually Lord Viṣṇu maintains and accomplishes all good fortune. If one has to take shelter of Lord Viṣṇu, why should the demigods take shelter of Lord Śiva? They did so because Lord Viṣṇu acts through Lord Śiva in the creation of the material world. Lord Śiva acts on behalf of Lord Viṣṇu. When the Lord says in Bhagavad-gītā (14.4) that He is the father of all living entities (ahaṁ bīja-pradaḥ pitā), this refers to actions performed by Lord Viṣṇu through Lord Śiva. Lord Viṣṇu is always unattached to material activities, and when material activities are to be performed, Lord Viṣṇu performs them through Lord Śiva. Lord Śiva is therefore worshiped on the level of Lord Viṣṇu. When Lord Viṣṇu is untouched by the external energy He is Lord Viṣṇu, but when He is in touch with the external energy, He appears in His feature as Lord Śiva.