Likewise, if one performeth the Obligatory Prayer with his heart in a state of utmost purity, he will obtain the confirmations of the Holy Spirit, and this will entirely obliterate love of self.

‘Abdu’l-Bahá, The Importance of Obligatory Prayer and Fasting

The mass of the people are occupied with self and worldly desire, are immersed in the ocean of the nether world and are captives of the world of nature, save those souls who have been freed from the chains and fetters of the material world and, like unto swift-flying birds, are soaring in this unbounded realm. They are awake and vigilant, they shun the obscurity of the world of nature, their highest wish centereth on the eradication from among men of the struggle for existence, the shining forth of the spirituality and the love of the realm on high, the exercise of utmost kindness among peoples, the realization of an intimate and close connection between religions and the practice of the ideal of self-sacrifice. Then will the world of humanity be transformed into the Kingdom of God.

‘Abdu’l-Bahá, Selections from the Writings of ‘Abdu’l-Bahá, p. 281-282

Today in the Orient those souls from amongst the various sects, religions and nations who have accepted the teachings of BAHA'O'LLAH are cemented together with the power of affinity and love. Were you to enter any of their conferences in the Orient you would behold the Mussulmans, Buddhists, Jews, Christians and Zoroastrians associating together in a spirit of unity and brotherhood to such degree that no one could differentiate one race from another. It is as though they had previously been opposing forces and were welded into one consciousness. These souls have reched the highest station of self-sacrifice.

‘Abdu’l-Bahá, Divine Philosophy, p. 181

We must be self-abnegating, we must have pure spirits, pure intentions, and strive with heart and soul while in the human world to attain everlasting glory.

‘Abdu’l-Bahá, The Promulgation of Universal Peace, p. 186

Self-sacrifice means to subordinate this lower nature and its desires to the more godly and noble side of ourselves. Ultimately, in its highest sense, self-sacrifice means to give our will and our all to God to do with as He pleases. Then He purifies and glorifies our true self until it becomes a shining and wonderful reality.

Shoghi Effendi, Lights of Guidance, p. 113-114

The Bahá’ís, in spite of their self-sacrificing desire to give the last drop of their strength to serving the Cause, must guard against utterly depleting their forces and having breakdowns. For this can sometimes do more harm than good, because they are so bound up in the lives of others.... "There is no doubt that there is vicarious atonement for others, and our sufferings sometimes can be in the nature of a sacrifice accepted for others. But where to draw the line is a mystery. If you take better care of your own health, and build up your reserves, it would certainly be better for you and for your work. Then your sensitive, yearning heart, although you may still often suffer for and with others, will be better able to withstand its trials, and you will not get so exhausted, which is certainly no asset to your work for the Cause.

Shoghi Effendi, Lights of Guidance, p. 279

The most earnest hope and desire of those who have drawn nigh to God is this -- to receive a cup from this ocean. I hope that in the service of God I may gain such a station as to put those who are in the way of God in the way of attaining the grace of self-sacrifice, that they may wholly forget their own personality and their ego. So long as the surface of the mirror is not clean from rust and dust, the radiance and effulgence of the sun shall never be imprinted on it. The more the body is lightened, the sooner it ascends.

Bahá’í Scriptures, p. 497