Shatapatha Brahmana 4.6.1.14

4.6.1.14

sa vā eṣa na sarvasyeva grahītavyaḥ | ātmā hyasyaiṣa yo nveva jñātastasya grahītavyo yo vāsya priyaḥ syādyo vānūcāno 'nūktenainam prāpnuyāt

This (graha) should not be drawn for every one, since this is his (Yagña's) self. It should only be drawn for one who is well known, or one who is his (the Adhvaryu's) friend, or one who, being learned in sacred lore, would acquire it by his study.