Brahmana Dharma (ब्राह्मणधर्मः)
According to Manusmrti,
अध्यापनम् अध्ययनं यजनं याजनं तथा । दानं प्रतिग्रहं चैव ब्राह्मणानाम् अकल्पयत् । । १.८८ । ।[1]
adhyāpanam adhyayanaṁ yajanaṁ yājanaṁ tathā । dānaṁ pratigrahaṁ caiva brāhmaṇānām akalpayat । । 1.88 । ।
Meaning: Studying, teaching, performing a sacrifice (either for oneself or for others), giving and accepting charity; these six are the responsibilities assigned to brahmanas (Manu Smrt. 1.88)[2] Talking of the importance of adhering to the Brahmana varna dharma, Manusmrti says,
आचारः परमो धर्मः श्रुत्युक्तः स्मार्त एव च । तस्मादस्मिन्सदा युक्तो नित्यं स्यादात्मवान्द्विजः । । १.१०८ । ।[1]
ācāraḥ paramo dharmaḥ śrutyuktaḥ smārta eva ca । tasmādasminsadā yukto nityaṁ syādātmavāndvijaḥ । । 1.108 । ।
Meaning: The Shrutis and Smrtis say that code of conduct is the highest duty; hence brahmanas must always be ready in adering to it (Manu Smrt. 1.108)[2] It says, a Brahmana who studies the shastras faithfully, according to the rules, is never tainted by sins arising from thoughts, words or deeds (Manu Smrt. 1.104). While, the one who deflects from his prescribed duties, doesn't obtain the fruit prescribed in the vedas; one who adheres to the code of conduct partakes in the fruit (Manu Smrt. 1.109)[2]
इदं शास्त्रम् अधीयानो ब्राह्मणः शंसितव्रतः । मनोवाग्गेहजैर्नित्यं कर्मदोषैर्न लिप्यते । । १.१०४ । ।
आचाराद्विच्युतो विप्रो न वेदफलम् अश्नुते । आचारेण तु संयुक्तः सम्पूर्णफलभाग्भवेत् । । १.१०९ । ।[1]
idaṁ śāstram adhīyāno brāhmaṇaḥ śaṁsitavrataḥ । manovāggehajairnityaṁ karmadoṣairna lipyate । । 1.104 । ।
ācārādvicyuto vipro na vedaphalam aśnute । ācāreṇa tu saṁyuktaḥ sampūrṇaphalabhāgbhavet । । 1.109 ।
Subsistence
A Brahmana shall not name his family and (Vedic) gotra in order to obtain a meal; for he who boasts of them for the sake of a meal, is called by the wise a foul feeder (vantasin). [v.3.109.]
A Brahmana must seek a means of subsistence which either causes no, or at least little pain (to others), and live (by that) except in times of distress. [v.4.2.]
For the purpose of gaining bare subsistence, let him accumulate property by (following those) irreproachable occupations (which are prescribed for) his (caste), without (unduly) fatiguing his body. [v.4.3.]