He was thinking: May the Lord of the universe, of whom I have taken shelter, kindly be pleased to offer me a son exactly like Him.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
शरणं तं प्रपद्येऽहं य एव जगदीश्वरः । प्रजामात्मसमां मह्यं प्रयच्छत्विति चिन्तयन्
śaraṇaṃ taṃ prapadye'haṃ ya eva jagadīśvaraḥ | prajāmātmasamāṃ mahyaṃ prayacchatviti cintayan
SB 4.1.20