Gita Chapter 18.41 to 18.45

Braahmanakshatriyavishaam shoodraanaam cha parantapa;
Karmaani pravibhaktaani swabhaavaprabhavairgunaih.
41. Of Brahmanas, Kshatriyas and Vaishyas, as also the Sudras, O Arjuna, the duties are distributed according to the qualities born of their own nature!

Shamo damastapah shaucham kshaantiraarjavameva cha;
Jnaanam vijnaanam aastikyam brahmakarma swabhaavajam.
42. Serenity, self-restraint, austerity, purity, forgiveness and also uprightness, knowledge, realisation and belief in God are the duties of the Brahmanas, born of (their own) nature.

Shauryam tejo dhritirdaakshyam yuddhe chaapyapalaayanam;
Daanameeshwarabhaavashcha kshaatram karmaswabhaavajam.
43. Prowess, splendour, firmness, dexterity and also not fleeing from battle, generosity and lordliness are the duties of Kshatriyas, born of (their own) nature.

Krishigaurakshyavaanijyam vaishyakarma swabhaavajam;
Paricharyaatmakam karma shoodrasyaapi swabhaavajam.
44. Agriculture, cattle-rearing and trade are the duties of the Vaishya (merchant class), born of (their own) nature; and action consisting of service is the duty of the Sudra (servant class), born of (their own) nature.
COMMENTARY: When a man does his duties rightly according to his order of life, his heart gets purified and he goes to heaven.

Swe swe karmanyabhiratah samsiddhim labhate narah;
Swakarmaniratah siddhim yathaa vindati tacchrinu.
45. Each man, devoted to his own duty, attains perfection. How he attains perfection while being engaged in his own duty, hear now.

Gita Chapter 17.21 to 17.25

Yattu pratyupakaaraartham phalamuddishya vaa punah;
Deeyate cha pariklishtam taddaanam raajasam smritam.
21. And, that gift which is made with a view to receive something in return, or looking for a reward, or given reluctantly, is said to be Rajasic.

Adeshakaale yaddaanamapaatrebhyashcha deeyate;
Asatkritamavajnaatam tattaamasamudaahritam.
22. The gift which is given at the wrong place and time to unworthy persons, without respect or with insult, is declared to be Tamasic.
COMMENTARY: At the wrong place and time—at a place which is not holy, where irreligious people and beggars assemble, where wealth acquired through illegal means such as gambling and theft, is distributed to gamblers, singers, fools, rogues, women of evil reputation; wealth that is distributed at an inauspicious time. This does not discourage the giving of alms to the poor.

Om tatsaditi nirdesho brahmanas trividhah smritah;
Braahmanaastena vedaashcha yajnaashcha vihitaah puraa.
23. “Om Tat Sat”: this has been declared to be the triple designation of Brahman. By that were created formerly the Brahmanas, the Vedas and the sacrifices.

Tasmaadomityudaahritya yajnadaanatapahkriyaah;
Pravartante vidhaanoktaah satatam brahmavaadinaam.
24. Therefore, with the utterance of “Om” are the acts of gift, sacrifice and austerity as enjoined in the scriptures always begun by the students of Brahman.

Tadityanabhisandhaaya phalam yajnatapah kriyaah;
Daanakriyaashcha vividhaah kriyante mokshakaangkshibhih.
25. Uttering Tat, without aiming at the fruits, are the acts of sacrifice and austerity and the various acts of gift performed by the seekers of liberation.