B.G 7.21-23
यो यो यां यां तनुं भक्तः श्रद्धयार्चितुमिच्छति। तस्य तस्याचलां श्रद्धां तामेव विदधाम्यहम् ॥२१॥
स तया श्रद्धया युक्तस्तस्याराधनमीहते। लभते च ततः कामान् मयैव विहितान् हि तान् ॥२२॥
अन्तवत्तु फलं तेषां तद्भवत्यल्पमेधसाम्। देवान् देवयजो यान्ति मद्भक्ता यान्ति मामपि ॥२३॥
yo yo yāṁ yāṁ tanuṁ bhaktaḥ śraddhayārcitumicchati। tasya tasyācalāṁ śraddhāṁ tāmeva vidadhāmyaham ॥21॥
sa tayā śraddhayā yuktastasyārādhanamīhate। labhate ca tataḥ kāmān mayaiva vihitān hi tān ॥22॥
antavattu phalaṁ teṣāṁ tadbhavatyalpamedhasām। devān devayajo yānti madbhaktā yānti māmapi ॥23॥
Whosoever desires to worship with faith whichever form (deity), I (the Supreme Lord) make that very faith of his steady and unwavering.
Endowed with that faith, he strives for the worship of that (deity) and obtains his desires, which are indeed granted by Me only.
Worshippers of the other gods with limited intelligence go to those gods and reap fruits that are perishable. But My devotees come to Me and reap (imperishable fruit) as well.
Gīta Bhāshya 7.21-23
Testimonials from Narada and Brahma-Vaivarta Purāṇa are provided to further substantiate the efficacy of showing devotion to Lord Krishna compared to worship of other deities.
'Whichever, Whichever' - expression indicates various forms beginning with Lord Brahmā.
It is stated in Nārada Purana:
"There is end (or boundary) for devotees of Brahmā and other lower deities, but there is no end to My (i.e. Lord Vishnu's) devotees."
-stated thus.
"What destination would the one, liberated, attain? And, of what nature is liberation itself?"
While providing the resolution to such statements, in the 'mokṣadharm' section of Mahabharata, it is stated:
"Among the incarnation of Lord Mahā Viṣṇu, the devotee gets liberated by worshiping any of the forms."
- such are the directions from the Brahma-Vaivarta Purāṇa.