As soon as His health permitted, Baha'u'llah began to teach inquirers and to encourage and exhort the believers, and soon peace and happiness reigned among the Babis. This, however, was short-lived. Baha'u'llah's half brother, Mirza Yahya, also known as Subh-i-Azal, arrived in Baghdad, and soon afterwards differences, secretly instigated by him, began to grow, just as similar divisions had arisen among the disciples of Christ. These differences (which later, in Adrianople, became open and violent) were very painful to Baha'u'llah.. (26:4)

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Baha'u'llah & the New Era
J. Esslemont