Only fools are ungrateful to their benefactors. The Lord, however, does not require benefit from anyone besides Himself because He is full in Himself; still He feels benefited by the unalloyed services of His devotees. The Lord feels grateful to His devotees for such unsophisticated, unconditional service and tries to reciprocate it by rendering service, although the devotee also has no such desire in his heart. The transcendental service of the Lord is itself a transcendental benefit for the devotee, and therefore
the devotee has nothing to expect from the Lord.
>>> Ref. VedaBase => SB 1.16.26-30 ppt