Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 9

Sanskrit:

सर्व एव यजन्ति त्वां सर्वदेवमयेश्वरम् ।येऽप्यन्यदेवताभक्ता यद्यप्यन्यधिय: प्रभो ॥ ९ ॥

ITRANS:

sarva eva yajanti tvāṁsarva-deva-mayeśvaramye ’py anya-devatā-bhaktāyady apy anya-dhiyaḥ prabho

Translation:

But all these people, my Lord, even those who have turned their attention away from You and are worshiping other deities, are actually worshiping You alone, O embodiment of all the demigods.

Purport:

The idea here is that even those who worship the demigods are indirectly worshiping the Supreme Lord Viṣṇu. The understanding of such worshipers, however, is imperfect.