Srimad Bhagavatam Canto 04, Chapter 29, Text 45

SB 4.29.45

sabda-brahmani duspare
 caranta uru-vistare
mantra-lingair vyavacchinnam
 bhajanto na viduh param
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Despite the cultivation of Vedic knowledge, which is unlimited, and the worship of different demigods by the symptoms of Vedic mantras, demigod worship does not help one to understand the supreme powerful Personality of Godhead.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
As stated in Bhagavad-gita (7.20):
 
kamais tais tair hrta-jñanah
 prapadyante ’nya-devatah
tam tam niyamam asthaya
 prakrtya niyatah svaya
 
“Those whose minds are distorted by material desires surrender unto demigods and follow the particular rules and regulations of worship according to their own natures.” Most people are interested in worshiping demigods to acquire powers. Each demigod has a particular power. For instance, the demigod Indra, the King of heaven, has power to shower rain on the surface of the globe to give sufficient vegetation to the earth. This demigod is described in the Vedas: vajra-hastah purandarah. Indra rules the water supply with a thunderbolt in his hand. The thunderbolt itself is controlled by Indra. Similarly, other demigods — Agni, Varuna, Candra, Surya — have particular powers. All these demigods are worshiped in the Vedic hymns through a symbolic weapon. Therefore it is said here, mantra-lingair vyavacchinnam. By such worship, karmis may obtain the benediction of material opulence in the form of animals, riches, beautiful wives, many followers, and so on. By such material opulence, however, one cannot understand the Supreme Personality of Godhead.
Srimad Bhagavatam Canto 04, Chapter 29, Text 42-44
Srimad Bhagavatam Canto 04, Chapter 29, Text 46