Even though Lord Siva was previously referred to in prayers by Lord Brahma as the Supreme, when Lord Visnu appeared, Siva also fell prostrated before Him to offer respectful obeisances

Expressions researched:
"Even though Lord Śiva was previously referred to in prayers by Lord Brahmā as the Supreme, when Lord Viṣṇu appeared, Śiva also fell prostrated before Him to offer respectful obeisances"

Srimad-Bhagavatam

SB Canto 4

Lord Viṣṇu is worshipable by all demigods, all Gandharvas and even Lord Śiva and Lord Brahmā. Tad viṣṇoḥ paramaṁ padaṁ sadā paśyanti sūrayaḥ: Viṣṇu is therefore the Supreme Personality of Godhead. Even though Lord Śiva was previously referred to in prayers by Lord Brahmā as the Supreme, when Lord Viṣṇu appeared, Śiva also fell prostrated before Him to offer respectful obeisances.

SB 4.7.22, Translation and Purport

As soon as Lord Viṣṇu was visible, all the demigods—Lord Brahmā and Lord Śiva, the Gandharvas and all present there—immediately offered their respectful obeisances by falling down straight before Him.

It appears that Lord Viṣṇu is the Supreme Lord even of Lord Śiva and Lord Brahmā, what to speak of the demigods, Gandharvas and ordinary living entities. It is stated in a prayer, yaṁ brahmā varuṇendra-rudra-marutāḥ: all the demigods worship Lord Viṣṇu. Similarly, dhyānāvasthita-tad-gatena manasā paśyanti yaṁ yoginaḥ: (SB 12.13.1) yogīs concentrate their minds on the form of Lord Viṣṇu. Thus Lord Viṣṇu is worshipable by all demigods, all Gandharvas and even Lord Śiva and Lord Brahmā. Tad viṣṇoḥ paramaṁ padaṁ sadā paśyanti sūrayaḥ: Viṣṇu is therefore the Supreme Personality of Godhead. Even though Lord Śiva was previously referred to in prayers by Lord Brahmā as the Supreme, when Lord Viṣṇu appeared, Śiva also fell prostrated before Him to offer respectful obeisances.