… gleaned from Baha’i literature

While in still a child, Baha’u’llah sought the dismissal of an unjust and tyrannical tax-collector

While still a child, the Blessed Beauty watched as a government tax-collector, on three separate occasions, accosted His father and demanded, in a cruel and unjust manner, the payment of taxes. Unable to bear the injustice of it all, He, though in early childhood, mounted His horse and rode for two days until He arrived in Tihran. There, He sought the dismissal of this unjust and tyrannical tax-collector. He succeeded in obtaining the necessary papers ordering the dismissal, and returned to His parents.
- 'Abdu'l-Baha (Words of 'Abdu'l-Baha recorded by Dr. Diya Baghdadidi, unpublished Memoirs; in 'Stories of Baha’u’llah', compiled by Ali-Akbar Furutan)

His short stature when seven years old

When Baha’u'llah was seven years old, one day His mother was watching the elegance of His bearing as He paced to and fro, and remarked 'He is somewhat short of stature.' but His father answered: 'It is of no importance. Are you not aware of His capacity and His abilities? Such intelligence! And such perception! He is as a flame of fire. Even at this young age He surpasses mature men.' Whenever difficult problems were discussed and no one seemed able to resolve them, the youthful Blessed Beauty would provide the solution.
- ‘Abdu’l-Baha  (Quoted by Ishraq-Khavari in Risaliy-i-Ayyam-i-Tis’ih p. 67; in 'Stories of Baha’u’llah', compiled by Ali-Akbar Furutan)

A Child with extraordinary powers of intellect, wisdom and innate knowledge - singled out among His siblings by relatives and family friends

From His earliest childhood Baha’u’llah was singled out among His siblings by relatives and family friends, whose composite opinion was that the Child had extraordinary powers of intellect, wisdom and innate knowledge, and was superior to others of his age and class. A common prediction applied to the little Baha’u’llah in that superstitious age of high child mortality was that 'such a precocious Child will not survive!' [1], for it was anticipated that child prodigies were especially fated to suffer early doom. All who encountered Him in those years of boyhood admitted that he was gifted in every way, and in addition was adorned with a rare purity and nobility. [2] 
- David Ruhe  (‘Robe of Light’)
[1] 'Abdu'l-Baha, quoted in Star of the West, Vol. 3, NO.9, p. 3 (1912)
[2] 'Abdu'l-Baha, ‘A Traveler's Narrative

Dreams at the age of five or six

At the age of five or six the Blessed Beauty had a dream which He described to His father. In the dream He found Himself in a garden. Huge birds were attacking Him from every side, but were unable to inflict any harm. He then went to the sea and, as He was swimming, the birds of the air and the fish of the sea attacked Him, but He was not harmed. His father summoned a famous seer to interpret the dream. 'This dream-indicates', replied the seer, 'that the Child shall be the founder of a great Cause, and that all the leaders and learned men throughout the world will attack Him, but, like the birds and the fish, they shall do no harm. He will be victorious over all.’
- ‘Abdu’l-Baha  (Quoted by Ishraq-Khavari in Risaliy-i-Ayyam-i-Tis’ih p. 65; in ‘Stories of Baha’u’llah’, compiled by Ali-Akbar Furutan)

"This Child never cries"

The mother of the Blessed Beauty was so enthralled with Him that she could not contain her amazement at His behaviour. 'This Child never cries,' she would say; 'He is so unlike other babies who cry and scream and are forever restless while in the nursing stage . . .'
- ‘Abdu’l-Baha  (Quoted by Ishraq-Khavari in Risaliy-i-Ayyam-i-Tis’ih p. 62; in ‘Stories of Baha’u’llah’, compiled by Ali-Akbar Furutan)