SB 1.6.15

tasmin nirmanuje ’raṇye
 pippalopastha āśritaḥ
ātmanātmānam ātmasthaṁ
 yathā-śrutam acintayam
Synonyms: 
tasmin — in that; nirmanuje — without human habitation; araṇye — in the forest; pippala — banyan tree; upasthe — sitting under it; āśritaḥ — taking shelter of; ātmanā — by intelligence; ātmānam — the Supersoul; ātma-stham — situated within myself; yathā-śrutam — as I had heard it from the liberated souls; acintayam — thought over.
Translation: 
After that, under the shadow of a banyan tree in an uninhabited forest I began to meditate upon the Supersoul situated within, using my intelligence, as I had learned from liberated souls.
Purport: 

One should not meditate according to one’s personal whims. One should know perfectly well from the authoritative sources of scriptures through the transparent medium of a bona fide spiritual master and by proper use of one’s trained intelligence for meditating upon the Supersoul dwelling within every living being. This consciousness is firmly developed by a devotee who has rendered loving service unto the Lord by carrying out the orders of the spiritual master. Śrī Nāradajī contacted bona fide spiritual masters, served them sincerely and got enlightenment rightly. Thus he began to meditate.