krsnera pratijna eka ache purva haite
ye yaiche bhaje, krsna tare bhaje taiche
Lord Krsna has a promise from before to reciprocate with His devotees according to the way they worship Him.
Adi 4.177
ye yatha mam prapadyante
tams tathaiva bhajamy aham
mama vartmanuvartante
manusyah partha sarvasah
As all surrender unto Me, I reward them accordingly. Everyone follows My path in all respects, O son of Prtha.
Bg 4.11
se pratijna bhanga haila gopira bhajane
tahate pramana krsna-sri-mukha-vacane
That promise h