Chapter IV Sloka 34

tiÍi¤ Ói[paten pirÓţen sevya, 
%pde˙yiNt te }an< }ainnSt┼vdizRn>.

tadviddhi pra§ipśtena 
paripra■nena sevayś | 
upadek yanti te j˝śnaŇ 
j˝śninastattvadar■inaÎ ( 4|34)||

Know That by long prostration, by question and by service, the wise who have realised the Truth will instruct thee in (That) Knowledge.
Commentary:

Go to the teachers (those who are well versed in the scriptures dealing with Brahman or Brahma-srotris, and who are established in Brahman or Brahmanishthas). Prostrate yourself before them with profound humility and perfect devotion. Ask them questions, "O venerable Guru! What is the cause of bondage? How can I get liberation? What is the nature of ignorance? What is the nature of knowledge? What is the Antaranga-Sadhana (inward spiritual practice) for attaining Self-realisation?" Serve the Guru whole-heartedly. A teacher who is versed in the scriptures (Sastras) but who has no direct Self-realisation will not be able to help you in the attainment of the knowledge of the Self. He who has knowledge of the Scriptures and who is also established in Brahman will be able to instruct thee in that knowledge and help thee in the attainment of Self-realisation. Mere prostrations alone will not do. They may be tinged with hypocrisy. You must have perfect faith in your Guru and his teaching. You must serve him whole-heartedly with great devotion.