SB 3.28.25

nābhi-hradaṁ bhuvana-kośa-guhodara-sthaṁ
 yatrātma-yoni-dhiṣaṇākhila-loka-padmam
vyūḍhaṁ harin-maṇi-vṛṣa-stanayor amuṣya
 dhyāyed dvayaṁ viśada-hāra-mayūkha-gauram
Synonyms: 
nābhi-hradam — the navel lake; bhuvana-kośa — of all the worlds; guhā — the foundation; udara — on the abdomen; stham — situated; yatra — where; ātma-yoni — of Brahmā; dhiṣaṇa — residence; akhila-loka — containing all planetary systems; padmam — lotus; vyūḍham — sprang up; harit-maṇi — like emeralds; vṛṣa — most exquisite; stanayoḥ — of nipples; amuṣya — of the Lord; dhyāyet — he should meditate on; dvayam — the pair; viśada — white; hāra — of pearl necklaces; mayūkha — from the light; gauram — whitish.
Translation: 
The yogī should then meditate on His moonlike navel in the center of His abdomen. From His navel, which is the foundation of the entire universe, sprang the lotus stem containing all the different planetary systems. The lotus is the residence of Brahmā, the first created being. In the same way, the yogī should concentrate his mind on the Lord’s nipples, which resemble a pair of most exquisite emeralds and which appear whitish because of the rays of the milk-white pearl necklaces adorning His chest.
Purport: 

The yogī is advised next to meditate upon the navel of the Lord, which is the foundation of all material creation. Just as a child is connected to his mother by the umbilical cord, so the first-born living creature, Brahmā, by the supreme will of the Lord, is connected to the Lord by a lotus stem. In the previous verse it was stated that the goddess of fortune, Lakṣmī, who engages in massaging the legs, ankles and thighs of the Lord, is called the mother of Brahmā, but actually Brahmā is born from the abdomen of the Lord, not from the abdomen of his mother. These are inconceivable conceptions of the Lord, and one should not think materially, “How can the father give birth to a child?”

It is explained in the Brahma-saṁhitā that each limb of the Lord has the potency of every other limb; because everything is spiritual, His parts are not conditioned. The Lord can see with His ears. The material ear can hear but cannot see, but we understand from the Brahma-saṁhitā that the Lord can also see with His ears and hear with His eyes. Any organ of His transcendental body can function as any other organ. His abdomen is the foundation of all the planetary systems. Brahmā holds the post of the creator of all planetary systems, but his engineering energy is generated from the abdomen of the Lord. Any creative function in the universe always has a direct connecting link with the Lord. The necklace of pearls which decorates the upper portion of the Lord’s body is also spiritual, and therefore the yogī is advised to gaze at the whitish luster of the pearls decorating His chest.