SB 11.7.38

śaśvat parārtha-sarvehaḥ
 parārthaikānta-sambhavaḥ
sādhuḥ śikṣeta bhū-bhṛtto
 naga-śiṣyaḥ parātmatām
Synonyms: 
śaśvat — always; para — of others; artha — for the sake; sarva-īhaḥ — all of one’s efforts; para-artha — the benefit of others; ekānta — sole; sambhavaḥ — reason for living; sādhuḥ — a saintly person; śikṣeta — should learn; bhū-bhṛttaḥ — from the mountain; naga-śiṣyaḥ — the disciple of the tree; para-ātmatām — dedication to others.
Translation: 
A saintly person should learn from the mountain to devote all his efforts to the service of others and to make the welfare of others the sole reason for his existence. Similarly, as the disciple of the tree, he should learn to dedicate himself to others.
Purport: 

Great mountains bear unlimited quantities of earth, which in turn give sustenance to innumerable forms of life such as trees, grass, birds, animals, and so on. Mountains also pour forth unlimited quantities of crystalline water in the form of waterfalls and rivers, and this water gives life to all. By studying the example of mountains, one should learn the art of providing for the happiness of all living entities. Similarly, one may take excellent lessons from the pious trees, who offer innumerable benefits, such as fruits, flowers, cooling shade and medicinal extracts. Even when a tree is suddenly cut down and dragged away, the tree does not protest but continues to give service to others in the form of firewood. Thus, one should become the disciple of such magnanimous trees and learn from them the qualities of saintly conduct.

According to Śrīla Madhvācārya, the word parārthaikānta-sambhavaḥ indicates that one should dedicate all of one’s wealth and other assets to the welfare of others. By one’s acquired opulence, one should especially try to please the spiritual master and the Supreme Personality of Godhead. Thus, the demigods, as well as all truly respectable superior personalities, will automatically be pleased. By developing saintly conduct, as described in this verse, one will become tolerant, and this will free one from the useless agitation of the material senses, which drive one to wander throughout the world searching in vain for material happiness. Lord Śrī Caitanya Mahāprabhu has also emphasized the tree’s quality of tolerance: taror iva sahiṣṇunā, kīrtanīyaḥ sadā hariḥ. One who is as tolerant as a tree can chant the holy name of Kṛṣṇa constantly, finding ever-new satisfaction.