देवतानाम गुरुनाम तथा मन्त्रं पूजाकालात् ऋते न उच्चारयेत्
Transliteration (IAST)
devatānāma gurunāma tathā mantraṃ pūjākālāt ṛte na uccārayet
The name of the deity, the name of the guru, and the mantra he should not pronounce except at the time of worship.