Buddha’s reference to Bahá’u’lláh

He [Bahá’u’lláh] alone is meant by the prophecy attributed to Gautama Buddha Himself, that “a Buddha named Maitreye, the Buddha of universal fellowship” should, in the fullness of time, arise and reveal “His boundless glory.” 

- Shoghi Effendi  ('God Passes By', chapter 6)

References to Bahá’u’lláh’s Dispensation from Zoroaster

To His [Bahá’u’lláh’s] Dispensation the sacred books of the followers of Zoroaster had referred as that in which the sun must needs be brought to a standstill for no less than one whole month. To Him Zoroaster must have alluded when, according to tradition, He foretold that a period of three thousand years of conflict and contention must needs precede the advent of the World-Savior Sháh-Bahrám, Who would triumph over Ahriman and usher in an era of blessedness and peace. 

- Shoghi Effendi  ('God Passes By', chapter 6)

References to Bahá’u’lláh by various Jewish prophets

•  Of Him [Bahá’u’lláh] David had sung in his Psalms, acclaiming Him as the “Lord of Hosts” and the “King of Glory.” 
• To Him Haggai had referred as the “Desire of all nations,” and 
• Zachariah as the “Branch” Who “shall grow up out of His place,” and “shall build the Temple of the Lord.” 
• Zachariah had extolled Him as the “Lord” Who “shall be king over all the earth,” 
• while to His day Joel and Zephaniah had both referred as the “day of Jehovah,” the latter describing it as “a day of wrath, a day of trouble and distress, a day of wasteness and desolation, a day of darkness and gloominess, a day of clouds and thick darkness, a day of the trumpet and alarm against the fenced cities, and against the high towers.” 
• His Day Ezekiel and Daniel had, moreover, both acclaimed as the “day of the Lord,” and 
• Malachi described as “the great and dreadful day of the Lord” when “the Sun of Righteousness” will “arise, with healing in His wings,” whilst 
• Daniel had pronounced His advent as signalizing the end of the “abomination that maketh desolate.” 

- Shoghi Effendi  ('God Passes By', chapter 6)

References to Bahá’u’lláh from Isaiah, “the greatest of Jewish prophets”

To Him Isaiah [Bahá’u’lláh], the greatest of the Jewish prophets, had alluded as 

• the “Glory of the Lord,” 
• the “Everlasting Father,” 
• the “Prince of Peace,” 
• the “Wonderful,” 
• the “Counsellor,” 
• the “Rod come forth out of the stem of Jesse” and 
• the “Branch grown out of His roots,” 
• Who “shall be established upon the throne of David,” 
• Who “will come with strong hand,” 
• Who “shall judge among the nations,” 
• Who “shall smite the earth with the rod of His mouth, and with the breath of His lips slay the wicked,” and 
• Who “shall assemble the outcasts of Israel, and gather together the dispersed of Judah from the four corners of the earth.” 

- Shoghi Effendi  ('God Passes By', chapter 6)

Bahá’u’lláh’s ancestral background

He [Bahá’u’lláh] derived His descent, on the one hand, from Abraham (the Father of the Faithful) through his wife Katurah, and on the other from Zoroaster, as well as from Yazdigird, the last king of the Sásáníyán dynasty. He was moreover a descendant of Jesse, and belonged, through His father, Mírzá ‘Abbás, better known as Mírzá Buzurg—a nobleman closely associated with the ministerial circles of the Court of Fatḥ-‘Alí Sháh—to one of the most ancient and renowned families of Mázindarán. 

- Shoghi Effendi  (God Passes By, chapter 6)