SB 12.10.10

bhagavāṁs tad abhijñāya
 giriśo yoga-māyayā
āviśat tad-guhākāśaṁ
 vāyuś chidram iveśvaraḥ
Word for word: 
bhagavān — the great personality; tat — that; abhijñāya — understanding; giriśaḥ — Lord Giriśa; yoga-māyayā — by his mystic power; āviśat — entered; tat — of Mārkaṇḍeya; guhā-ākāśam — the hidden sky of the heart; vāyuḥ — the air; chidram — a hole; iva — as if; īśvaraḥ — the lord.
Translation: 
Understanding the situation very well, the powerful Lord Śiva employed his mystic power to enter within the sky of Mārkaṇḍeya’s heart, just as the wind passes through an opening.