SB 4.20.4
purusa yadi muhyanti
tvadrsa deva-mayaya
srama eva param jato
dirghaya vrddha-sevaya
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
If a personality like you, who are so much advanced because of executing the instructions of the previous acaryas, is carried away by the influence of My material energy, then all your advancement may be considered simply a waste of time.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In this verse the word vrddha-sevaya is very significant. Vrddha means “old”; sevaya means “by service.” Perfect knowledge is acquired from the acaryas, or liberated souls. No one can be perfect in knowledge without being trained by the parampara system. Prthu Maharaja was completely trained in that line; therefore he did not deserve to be considered an ordinary man. An ordinary man, who has only a conception of bodily existence, is always bewildered by the modes of material nature.