It is Baha'u'llah Who, in the Old Testament hath been named YHWH (Jehovah)

In a number of his epistles of the late ‘Akka period, Baha’u’llah clearly claimed to be YHWH, the Divinity Who conversed with Moses from the burning bush and whose eschatological advent as “YHWH of hosts” (“the Lord of hosts’’) was predicted by the Israelite prophets. In, for example, the following lines addressed to a Jewish convert to the Baha’i Faith named Aga Jan, Baha’u’llah writes:

The Face of the Ancient One [Baha’u’llah] hath turned towards the sages (hukama) in the Land of al-ha and al-mim [Hamdadan, in Iran] and announceth unto them the glad-tidings of the Ridvan (Paradise) of God, the Lord of all the worlds: “By God! He Who hath been named YHWH ‘‘Jehovah” in the Torah hath come.

On similar lines is the following extract from an epistle of Baha’u’llah to the Baha’i poet ‘Andalib (and others):

He [Baha’u’llah] it is Who, in the Old Testament (Torah) hath been named YHWH “Jehovah”...

A good many passages are to be found in the Tablets of the late ‘Akka period in which Baha’u’llah refers to himself as “the Lord (YHWH) of hosts” (Arabic: rabb al-junud). One such passage reads as follows:

This is the Day in which He Who cried out on the Mount (munadi at-tur) hath held converse and the Lord of Hosts (rabb al-junud) proclaimed before all the world: ‘‘No God is there except Me, the Mighty, the Knowing.’’

‘Abdu’l-Baha specifically identified the Biblical ‘‘Lord of Hosts’’ with his father and spoke of the “hosts’’ as the stalwart members of the Baha’i community.”

(Stephen Lambden in "Studies in the Babi and Baha’i Religions (formerly Studies in Babi and Baha’i History) Volume Five)