CC Madhya 24.93

ajā-gala-stana-nyāya anya sādhana
ataeva hari bhaje buddhimān jana

ajā-gala-stana-nyāya—like the nipples on the neck of a goat; anya—other; sādhana—execution of spiritual life; ataeva—therefore; hari—the Supreme Personality of Godhead; bhaje—one worships; buddhimān jana—the intelligent person.

“With the exception of devotional service, all the methods of self-realization are like the nipples on the neck of a goat. Therefore an intelligent person adopts only devotional service, giving up all other processes of self-realization.

Without devotional service, other methods for self-realization and spiritual life are useless. Other methods cannot produce good results at any time, and therefore they are compared to the nipples on the neck of a goat. These nipples cannot produce milk, although it may appear that they can. An unintelligent person cannot understand that only devotional service can elevate one to the transcendental position.