SB 6.18.8

urukramasya devasya
 māyā-vāmana-rūpiṇaḥ
kīrtau patnyāṁ bṛhacchlokas
 tasyāsan saubhagādayaḥ
Synonyms: 
urukramasya — of Urukrama; devasya — the Lord; māyā — by His internal potency; vāmana-rūpiṇaḥ — having the form of a dwarf; kīrtau — in Kīrti; patnyām — His wife; bṛhacchlokaḥ — Bṛhatśloka; tasya — of him; āsan — were; saubhaga-ādayaḥ — sons beginning with Saubhaga.
Translation: 
By His own potency, the Supreme Personality of Godhead, who has multifarious potencies, appeared in the form of a dwarf as Urukrama, the twelfth son of Aditi. In the womb of His wife, whose name was Kīrti, He begot one son, named Bṛhatśloka, who had many sons, headed by Saubhaga.
Purport: 

As the Lord says in Bhagavad-gītā (4.6):

ajo ’pi sann avyayātmā
 bhūtānām īśvaro ’pi san
prakṛtiṁ svām adhiṣṭhāya
 sambhavāmy ātma-māyayā

“Although I am unborn and My transcendental body never deteriorates, and although I am the Lord of all sentient beings, I still appear in every millennium in My original transcendental form.” When the Supreme Personality of Godhead incarnates, He does not need any help from the external energy, for He appears as He is by His own potency. The spiritual potency is also called māyā. It is said, ato māyāmayaṁ viṣṇuṁ pravadanti manīṣiṇaḥ: the body accepted by the Supreme Personality of Godhead is called māyāmaya. This does not mean that He is formed of the external energy; this māyā refers to His internal potency.