The Greatest Name is the Name of Bahá’u’lláh. “
Yá Bahá’u’l-Abhá” is an invocation meaning: “O Thou Glory of Glories!”. “Alláh-u-Abhá” is a greeting which means: “God the All-Glorious”. Both refer to Bahá’u’lláh. By Greatest Name is meant that Bahá’u’lláh has appeared in God’s Greatest Name, in other words, that He is the supreme
Manifestation of God.