Srimad Bhagavatam Canto 04, Chapter 21, Text 50

SB 4.21.50

natyadbhutam idam natha
prajanurago mahatam
 prakrtih karunatmanam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Our dear lord, it is your occupational duty to rule over your citizens. That is not a very wonderful task for a personality like you, who are so affectionate in seeing to the interests of the citizens, because you are full of mercy. That is the greatness of your character.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
A king’s duty is to give protection to his citizens and levy taxes from them for his livelihood. Since the Vedic society is divided into four classes of men — the brahmanas, ksatriyas, vaisyas and sudras — their means of livelihood are also mentioned in the scriptures. The brahmanas should live by spreading knowledge and should therefore take contributions from their disciples, whereas a king should give protection to the citizens for their development to the highest standard of life, and he can therefore levy taxes from them; businessmen or mercantile men, because they produce foodstuffs for the whole of society, can take a little profit from this, whereas the sudras, who cannot work as either brahmanas, ksatriyas or vaisyas, should give service to the higher classes of society and be provided by them with a supply of the necessities of life.
The symptom of a qualified king or political leader is mentioned herein: he must be very merciful and compassionate to the people and see to their prime interest, which is to become elevated devotees of the Supreme Personality of Godhead. Great souls are naturally inclined to do good to others, and a Vaisnava especially is the most compassionate and merciful personality in society. Therefore we offer our respects to a Vaisnava leader as follows:
vañcha-kalpatarubhyas ca
 krpa-sindhubhya eva ca
patitanam pavanebhyo
 vaisnavebhyo namo namah
Only a Vaisnava leader can fulfill all the desires of the people (vañcha-kalpataru), and he is compassionate because he is the contributor of the greatest benefit to human society. He is patita-pavana, the deliverer of all fallen souls, because if the king or the head of the government follows in the footsteps of the brahmanas and Vaisnavas, who are naturally leaders in missionary work, the vaisyas will also follow in the footsteps of the Vaisnavas and brahmanas, and the sudras will give them service. Thus the entire society becomes a perfect human institution for combined progress to the highest perfection of life.
Srimad Bhagavatam Canto 04, Chapter 21, Text 49
Srimad Bhagavatam Canto 04, Chapter 21, Text 51