Shiva Purana
तच्छ्रुत्वा गुरुसंदेशं क्रमशो मंत्रसाधकः ॥ पुरतो विनियोगस्य मन्त्रसाधनमाचरेत् ॥ ८ ॥
Hearing the message of his spiritual master, he gradually performed the mantra. One should perform the mantra means of the initiation in front of him.
english translation
tacchrutvA gurusaMdezaM kramazo maMtrasAdhakaH ॥ purato viniyogasya mantrasAdhanamAcaret ॥ 8 ॥
hk transliteration by Sanscript