The brāhmaṇas, who were completely expert in chanting the Vedic hymns, were all yogīs fully equipped with mystic powers. Whatever blessings they spoke were certainly never fruitless.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
विप्रा मन्त्रविदो युक्तास्तैर्याः प्रोक्तास्तथाऽऽशिषः । ता निष्फला भविष्यन्ति न कदाचिदपि स्फुटम्
viprā mantravido yuktāstairyāḥ proktāstathā''śiṣaḥ | tā niṣphalā bhaviṣyanti na kadācidapi sphuṭam
SB 10.7.17