SB 2.10.28

āsisṛpsoḥ puraḥ puryā
 nābhi-dvāram apānataḥ
tatrāpānas tato mṛtyuḥ
 pṛthaktvam ubhayāśrayam
Synonyms: 
āsisṛpsoḥ — desiring to go everywhere; puraḥ — in different bodies; puryāḥ — from one body; nābhi-dvāram — the navel or abdominal hole; apānataḥ — was manifested; tatra — thereupon; apānaḥ — stopping of the vital force; tataḥ — thereafter; mṛtyuḥ — death; pṛthaktvam — separately; ubhaya — both; āśrayam — shelter.
Translation: 
Thereafter, when He desired to move from one body to another, the navel and the air of departure and death were combinedly created. The navel is the shelter for both, namely death and the separating force.
Purport: 

The prāṇa-vāyu continues the life, and the apāna-vāyu stops the living force. Both the vibrations are generated from the abdominal hole, the navel. This navel is the joint from one body to the other. Lord Brahmā was born of the abdominal hole of Garbhodakaśāyī Viṣṇu as a separate body, and the same principle is followed even in the birth of any ordinary body. The body of the child develops from the body of the mother, and when the child is separated from the body of the mother, it is separated by cutting the navel joint. And that is the way the Supreme Lord manifested Himself as separated many. The living entities are therefore separated parts, and thus they have no independence.