Kirat Karō is one of the Three pillars of Sikhism

Three pillars of Sikhism

The Three Pillars of Sikhism were formalised by Guru Nanak as:#The Guru led the Sikhs directly to practise Simran and Naam Japna—meditation on God and reciting and chanting of God’s Name—Waheguru...

, the others being Naam Japo and Vaṇḍ chakkō. The term means to earn an honest, pure and dedicated living by exercising one's God-given skills, abilities, talents and hard labour for the benefit and improvement of the individual, their family and society at large. This means to work with determination and focus by the sweat of one's brow and not to be lazy and to waste one's life to time. Meanwhile, Simran and dedication to the work of God, not personal gain, should be one's main motivation.

In the Guru Granth Sahib

Guru Granth Sahib

Sri Guru Granth Sahib , or Adi Granth, is the religious text of Sikhism. It is the final and eternal guru of the Sikhs. It is a voluminous text of 1430 angs, compiled and composed during the period of Sikh gurus, from 1469 to 1708...

, Guru Arjan Dev

Guru Arjan Dev

Guru Arjan Dev Ji was the fifth of the Ten Gurus of Sikhism. He was born in Goindval, Punjab, India, the youngest son of Guru Ram Das and Bibi Bhani, the daughter of Guru Amar Das. He became the Guru of the Sikhs on 1 September 1581 after the death of his father Guru Ram Das. Guru Arjan died in...

says: "Those who have meditated on the Naam, the Name of the Lord, and departed after having worked by the sweat of their brows
-O Nanak, their faces are radiant in the Court of the Lord, and many are saved along with them!"

Other relevant passages: