Practise Truthfulness and Sincerity

Swami Turiyananda (a direct disciple of Swami Sri Ramakrishnan Paramahamsa): "Sincerity is the backbone of spirituality. One should practise it in one's actions and thoughts. There should be no disagreement between what one feels and what one says... Make your heart and tongue one." (pg. 377, God Lived with Them by Swami Chetanananda)

"...If everyone were insincere with everyone else, what pandemonium there would be! Suppose you tell someone that you are going to meditate, but instead your intention is to slip off to do some wrong against him; that is treachery, insincerity in its worst form....Give love and unselfishness, and you will receive love and unselfishness. But express greed, selfishness, jealousy, and you will attract in kind," Paramahansa Yogananda (pg. 77, The Divine Romance)

"Loyalty to a spiritual custom without sincerity and conviction his hypocrisy. Loyalty to the spirit of a custom even without clinging to a form is wisdom. But loyalty neither to spiritual custom nor principle, nor teacher is spiritual degeneration. Stand by God any His servants, and you'll see his hand working through all things." (May 17, Paramahansa Yogananda, Spiritual Diary).

"Nothing is impossible for a person who has a firm determination, sincerity of purpose, iron will, perseverance and patience." (pg 458, commentary Gita 17:15 by Swami Sivananda).

"If you perform sacrifice, austerity, charity and all other actions in a spirit of total surrender to the Lord or the Eternal Being, with purity and sincerity of heart, you will attain the highest goal of life or immortality, freedom and eternal bliss." (pg 467, commentary on Gita 17:27 by Swami Sivananda  Gita 17:27).