Yajurveda Samhita specifically states in the second verse (26.2) that the sage should speak the secret knowledge to all the persons, regardless of their status, profession or familiarity. The blissful Word should be taught to the shūdra (labouring class) also; In this verse shūdra takes precedence over the artisans (vaishyās). Again this verse calls upon the knowledge to be given even to the stranger chāraņāya and to our own members svāya.
So that I may speak the blissful Word to the masses of the people,
to the brāhmaņa and the rajanya (kşhatriya),
to the shūdra and the vaishya,
to our own men and to the stranger.
Dear may I be to the devās and to the giver of the sacred gifts here.
May this my wish prosper; may that be mine. SYV (26.2)