Taittiriya Upanishad 1.6

भूत्यै न प्रमदितव्यम् | स्वाध्यायप्रवचनाभ्यां न प्रमदितव्यम् | मातृदेवो भव | पितृदेवो भव | आचार्यदेवो भव | अतिथिदेवो भव ॥

bhutyai na pramaditavyam | svadhyaya-pravachanabhyam na pramaditavyam | matri-devo bhava | pitri-devo bhava | acharya-devo bhava | atithi-devo bhava ||

'There must be no negligence of prosperity. There must be no negligence of study and teaching. Be one to whom the mother is a god. Be one to whom the father is a god. Be one to whom the teacher is a god. Be one to whom the guest is a god.'

‘ऐश्वर्य से प्रमाद मत करना। स्वाध्याय और प्रवचन से प्रमाद मत करना। माता को देव-तुल्य मानो। पिता को देव-तुल्य मानो। आचार्य को देव-तुल्य मानो। अतिथि को देव-तुल्य मानो।’