Rank is a fragile thing in the Day of God. Bahá’u’lláh declares that the highest among the people have been made lowest and the lowest highest, and He calls this the mystery of the Great Reversal in the Sign of the Sovereign. Learned men who believed they had climbed to the summit of knowledge stayed veiled from the Sun of Truth, while souls whose names no one had ever mentioned heard the call and answered it. A shepherd is remembered before the Throne; the owner of earthly treasure is forgotten. ‘Abdu’l-Bahá adds that divine tests always bring down the great and raise the lowly, as every past Manifestation has shown. Mary sang of the mighty cast down and the humble lifted up [1], and her song belongs to the same long overturning. For anyone proud of position or discouraged by obscurity, the teaching cuts both ways. It also opens toward the hidden language of letters, numbers and symbols in which such mysteries are written, and toward the convulsions of a world whose old order of greatness is being shaken.
This is a Day wherein God hath made the highest among the people lowest, and the lowest highest. Observe how many souls who deemed themselves to have ascended to the loftiest heights of knowledge and learning remained yet veiled from the Sun of Truth, while how many whose names were never mentioned, after the call of the Lord of Names was raised between earth and heaven, turned to the most exalted horizon and quaffed the purest wine.
(Bahá’u’lláh, 1292-06-03 [1875-Jul-7], to Jinab-i-Haji Mulla Baqir -- BH02735)
02
Regard thou, O friend, the mystery of the Great Reversal in the Sign of the Sovereign. Through this reversal He hath caused the exalted to be abased and the abased to be exalted.
(Bahá’u’lláh, Lawh-i-Hirtik (Tablet to David Hardegg), to Georg David Hardegg -- BH01217)
03
Regarding what you asked about "the mystery of the great reversal in the sign of the sovereign", at the first appearance [of the Manifestation], observe how Shaykh Muhammad Hasan Najafi, who was the pole of Iranian scholars, and other scholars of Najaf and the land of Taff and the countries of Iran, after the Word was raised up and the Cause declared, all were found to be veiled and shut out. They were deprived of the ocean of the Merciful's utterance and heedless of the sun of knowledge. Rather, they occupied themselves with cursing and execration from the pulpits. They rejected that Essence of being Whom they had yearned and hoped to meet throughout centuries and ages, and at the mention of Whose name they would say "may God hasten." Finally they issued the fatwa of death for His most pure blood. However, some among the common people turned to Him, drank from the ocean of divine knowledge, found their way to the highest horizon, and on the day of the raising of the Most Exalted Pen's voice were blessed to say "Here am I." Thus did We make their highest ones lowest and their lowest ones highest. This is the mystery of "the great reversal in the sign of the sovereign."
(Bahá’u’lláh, 1305 ? [1887-1888], to Aqa Mirza Muhammad Hasan, et al -- BH00548)
04
And concerning His words "the mystery of the great reversal in the sign of the sovereign," this refers to the tradition "He maketh their highest to be their lowest, and their lowest to be their highest." Observe how the chiefs who occupied the highest station descended to the lowest station - this is the mystery of the great reversal, and this reversal appeared from the symbols and intimations of the Sovereign. After the appearance of the blessed word "He" in the garment of "I," heaven was rolled up, the sun was darkened, the stars fell, and the earth was cleft asunder. How many divines who considered themselves oceans of knowledge were, by the aforementioned word, returned to the worst of stations, nay, were brought to naught, and how many servants who were remembered in no gathering were, by virtue of their acceptance, reckoned among the denizens of the highest heaven. These are the leaves of the scrolls, the words of the Psalms, and the letters of the Book. The jewels of the world were extracted from the retort and alembic of wisdom and utterance, which is the Supreme Pen, by His command - and He is the Ordainer, the All-Wise.
This is the truth. But we must know also that in the divine tests, changes always come; the great among us have to fall down, and the low ones have to rise. This has been shown in all the Manifestations of the past. In the Koran it says that when the great test comes, the high will fall low, and the low will rise high...
The available source contains an omission or incomplete wording; sentence boundaries need review.
06
This is a Day wherein We have made the highest among the people their lowest, and their lowest their highest, and We have made those who were oppressed the inheritors of the Kingdom, even as We promised them aforetime.
(Bahá’u’lláh, ca. 1289-1290?, to Muhammad -- BH03555)
07
This is why it was said aforetime: "We shall make their highest ones their lowest ones, and their lowest ones their highest ones."
(Bahá’u’lláh, 1293-01 [1876-Jan], to Rafi'u'ddin Khan -- BH06912)
08
The shepherd hath been mentioned before the Throne, while forgotten was he who possessed the treasures of the earth and enjoyed a mighty portion. This is a Day wherein We have made the highest among the people lowest, and the lowest highest. Thy Lord, verily, is the Almighty, the Powerful. How many were possessed of glory who were turned away from the door, and how many were abased who entered and attained, exclaiming: "Praise be to God Who hath made me to achieve this noble vision!"
(Bahá’u’lláh, ca. 1289-1290?, to Qurban -- BH03620)