One verse

Srimad Bhagavatam 9.14.48

9.14.48

एक एव पुरा वेद: प्रणव: सर्ववाङ्‌मय: । देवो नारायणो नान्य एकोऽग्निर्वर्ण एव च ॥ ४८ ॥

eka eva pura vedah pranavah sarva-vanmayah devo narayano nanya eko ’gnir varna eva ca

ekah
only one
eva
indeed
pura
formerly
vedah
book of transcendental knowledge
pranavah
omkara
sarva-vak-mayah
consisting of all Vedic mantras
devah
the Lord, God
narayanah
only Narayana (was worshipable in the Satya-yuga)
na anyah
no other
ekah agnih
one division only for agni
varnah
order of life
eva ca
and certainly.

In the Satya-yuga, the first millennium, all the Vedic mantras were included in one mantra—pranava, the root of all Vedic mantras. In other words, the Atharva Veda alone was the source of all Vedic knowledge. The Supreme Personality of Godhead Narayana was the only worshipable Deity; there was no recommendation for worship of the demigods. Fire was one only, and the only order of life in human society was known as hamsa.