Suitable (SB cantos 7 - 12)
Srimad-Bhagavatam
SB Canto 7
SB 7.3.30, Purport:
The Vedic ritualistic ceremonies, the knowledge thereof, and the person who agrees to perform them are inspired by the Supreme Soul. As confirmed in Bhagavad-gītā, mattaḥ smṛtir jñānam apohanaṁ ca: (BG 15.15) from the Lord come remembrance, knowledge and forgetfulness. The Supersoul is situated in everyone's heart (sarvasya cāhaṁ hṛdi sanniviṣṭaḥ, īśvaraḥ sarva-bhūtānāṁ hṛd-deśe 'rjuna tiṣṭhati (BG 18.61)), and when one is advanced in Vedic knowledge, the Supersoul gives him directions. Acting as Supersoul, the Lord gives inspiration to a suitable person to perform the Vedic ritualistic ceremonies. In this connection, four classes of priests, known as ṛtvik, are required. They are mentioned as hotā, adhvaryu, brahma and udgātā.