First of all, in the beginning of creation, there were the four unmarried sons of Brahmā [the Kumāras], who, being situated in a vow of celibacy, underwent severe austerities for realization of the Absolute Truth.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
स एव प्रथमं देवः कौमारं सर्गमाश्रितः । (सर्गमास्थितः) चचार दुश्चरं ब्रह्मा ब्रह्मचर्यमखण्डितम्
sa eva prathamaṃ devaḥ kaumāraṃ sargamāśritaḥ | (sargamāsthitaḥ) cacāra duścaraṃ brahmā brahmacaryamakhaṇḍitam
SB 1.3.6