He used to ride a white donkey. It was called Barq [lightning] because of its ability to move fast. Any time He went from the Mansion to the Garden of Ridvan, to Mazra'ih, to the Garden of Junaynih, or to Akka, He rode on that donkey, and returned in the same way to the Mansion. On these trips a servant always accompanied Him. Later when Barq died they brought another donkey from Persia... it was called Ra'd [thunder].

[Taherzadeh, The Revelation of Baha'u'llah Vol 4. page 105]

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