"Adversity is the oil which feedeth the flame of this Lamp and by which its light is increased, did ye but know."

"Say: This Youth hath departed out of this country and deposited beneath every tree and every stone a trust, which God will erelong bring forth through the power of truth. Thus hath the True One come and the command of Him Who is the Ordainer, the All-Wise, been fulfilled. The hosts of earth and heaven are powerless to resist His Cause, nor can all the kings and rulers of the world ever frustrate His purpose. Say: Adversity is the oil which feedeth the flame of this Lamp and by which its light is increased, did ye but know. Indeed, the repudiation of the froward serveth but to proclaim this Faith and to spread the Cause of God and His Revelation throughout the world."

-Bahá'u'lláh, The Summons of the Lord of Hosts, Súriy-i-Ra’ís, pp. 146-147