SB 4.6.39

taṁ brahma-nirvāṇa-samādhim āśritaṁ
 vyupāśritaṁ giriśaṁ yoga-kakṣām
sa-loka-pālā munayo manūnām
 ādyaṁ manuṁ prāñjalayaḥ praṇemuḥ
Synonyms: 
tam — him (Lord Śiva); brahma-nirvāṇa — in brahmānanda; samādhim — in trance; āśritam — absorbed; vyupāśritam — leaning on; giriśam — Lord Śiva; yoga-kakṣām — having his left knee firmly fixed with a knotted cloth; sa-loka-pālāḥ — along with the demigods (headed by Indra); munayaḥ — the sages; manūnām — of all thinkers; ādyam — the chief; manum — thinker; prāñjalayaḥ — with folded palms; praṇemuḥ — offered respectful obeisances.
Translation: 
All the sages and demigods, headed by Indra, offered their respectful obeisances unto Lord Śiva with folded hands. Lord Śiva was dressed in saffron garments and absorbed in trance, thus appearing to be the foremost of all sages.
Purport: 

In this verse the word brahmānanda is significant. This brahmānanda, or brahma-nirvāṇa, is explained by Prahlāda Mahārāja. When one is completely absorbed in the adhokṣaja, the Supreme Personality of Godhead, who is beyond the sense perception of materialistic persons, one is situated in brahmānanda.

It is impossible to conceive of the existence, name, form, quality and pastimes of the Supreme Personality of Godhead because He is transcendentally situated beyond the conception of materialistic persons. Because materialists cannot imagine or conceive of the Supreme Personality of Godhead, they may think that God is dead, but factually He is always existing in His sac-cid-ānanda-vigraha, His eternal form. Constant meditation concentrated on the form of the Lord is called samādhi — ecstasy or trance. Samādhi means particularly concentrated attention, so one who has achieved the qualification of always meditating on the Personality of Godhead is to be understood to be always in trance and enjoying brahma-nirvāṇa, or brahmānanda. Lord Śiva exhibited those symptoms, and therefore it is stated that he was absorbed in brahmānanda.

Another significant word is yoga-kakṣām. Yoga-kakṣā is the sitting posture in which the left thigh is fixed under one’s tightly knotted saffron-colored garment. Also the words manūnām ādyam are significant here because they mean a philosopher, or one who is thoughtful and can think very nicely. Such a man is called manu. Lord Śiva is described in this verse as the chief of all thinkers. Lord Śiva, of course, does not engage in useless mental speculation, but as stated in the previous verse, he is always thoughtful regarding how to deliver the demons from their fallen condition of life. It is said that during the advent of Lord Caitanya, Sadāśiva appeared as Advaita Prabhu, and Advaita Prabhu’s chief concern was to elevate the fallen conditioned souls to the platform of devotional service to Lord Kṛṣṇa. Since people were engaged in useless occupations which would continue their material existence, Lord Śiva, in the form of Lord Advaita, appealed to the Supreme Lord to appear as Lord Caitanya to deliver these illusioned souls. Actually Lord Caitanya appeared on the request of Lord Advaita. Similarly, Lord Śiva has a sampradāya, the Rudra sampradāya. He is always thinking about the deliverance of the fallen souls, as exhibited by Lord Advaita Prabhu.