Srimad-Bhagavatam: Canto 9 - Chapter 1 - Verse 11
Sanskrit:
अन्तर्वत्न्यागते काले यमौ सा सुषुवे सुतौ ।कुशो लव इति ख्यातौ तयोश्चक्रे क्रिया मुनि: ॥ ११ ॥
ITRANS:
antarvatny āgate kāleyamau sā suṣuve sutaukuśo lava iti khyātautayoś cakre kriyā muniḥ
Translation:
When the time came, the pregnant mother Sītādevī gave birth to twin sons, later celebrated as Lava and Kuśa. The ritualistic ceremonies for their birth were performed by Vālmīki Muni.