Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 26
Sanskrit:
अग्न्यर्काचार्यगोविप्रगुरुवृद्धसुराञ्शुचि: ।समाहित उपासीत सन्ध्ये द्वे यतवाग् जपन् ॥ २६ ॥
ITRANS:
agny-arkācārya-go-vipra-guru-vṛddha-surāñ śuciḥsamāhita upāsītasandhye dve yata-vāg japan
Translation:
Purified and fixed in consciousness, the brahmacārī should worship the fire-god, sun, ācārya, cows, brāhmaṇas, guru, elderly respectable persons and demigods. He should perform such worship at sunrise and sunset, without speaking but by silently chanting or murmuring the appropriate mantras.