B.G 4.11
ये यथा मां प्रपद्यन्ते तांस्तथैव भजाम्यहम्। मम वर्त्मानुवर्तन्ते मनुष्याः पार्थ सर्वशः ॥११॥
As they worship Me, accordingly I reciprocate to them. O Arjuna, humans are subsurvient to my ways in all aspects.
Gīta Tātparya 4.11
"tathaiva bhajāmi" = I give results accordingly. Even the worship of other deities must ultimately be dedicated to Lord Vishnu in order to yield results.
तथैव भजामि तदनुसारिफलदानरूपेण। अन्यदेवतायाजिनामपि मत्समर्पणेन वैष्णवमार्गानुवर्तनेनैव सम्यक् फलं भवति।
The words "tathaiva bhajāmi" mean "I give results accordingly". Even the worshippers of other deities dedicate to me only, but following directly Vaishnavism produces better results.
अन्यदैवतपूजाऽपि यस्मिन्नन्ते समर्पिता। स्वर्गादिफलहेतुः स्यात् नान्यथा तं भजेद्धरिम्॥
इत्याग्नेये ॥११-१२॥
"Even the worship of other deities becomes the cause of heaven and other rewards, only when they are dedicated to lord Vishnu in the end, not otherwise."
-states Agni Purana.