After His return from this retirement, His fame became greater than ever and people flocked to Baghdád from far and near to see Him and hear His teachings. Jews, Christians and Zoroastrians, as well as Muhammadans, became interested in the new message. The Mullás (Muhammadan doctors), however, took up a hostile attitude and persistently plotted to effect His overthrow. On a certain occasion they sent one of their number to interview Him and submit to Him certain questions. The envoy found the answers of Bahá’u’lláh so convincing and His wisdom so amazing, although evidently not acquired by study, that he was obliged to confess that in knowledge and understanding Bahá’u’lláh was peerless. In order, however, that the Mullás who had sent him should be satisfied as to the reality of Bahá’u’lláh’s Prophethood, he asked that some miracle should be produced as proof. Bahá’u’lláh expressed His willingness to accept the suggestion on certain conditions, declaring that if the Mullás would agree regarding some miracle to be performed, and would sign and seal a document to the effect that on performance of this miracle they would confess the validity of His mission and cease to oppose Him, 29 He would furnish the desired proof or else stand convicted of imposture. Had the aim of the Mullás been to get at the truth, surely here was their opportunity; but their intention was far otherwise. Rightly or wrongly, they meant to secure a decision in their own favor. They feared the truth and fled from the daring challenge. This discomfiture, however, only spurred them on to devise fresh plots for the eradication of the oppressed sect. The Consul General of Persia in Baghdád came to their assistance and sent repeated messages to the Sháh to the effect that Bahá’u’lláh was injuring the Muhammadan religion more than ever, still exerting a malign influence on Persia, and that He ought therefore to be banished to some more distant place.

It was characteristic of Bahá’u’lláh that, at this crisis, when at the instigation of the Muhammadan Mullás the Persian and Turkish Governments were combining their efforts to eradicate the Movement, He remained calm and serene, encouraging and inspiring His followers and writing imperishable words of consolation and guidance. ‘Abdu’l-Bahá relates how the Hidden Words were written at this time. Bahá’u’lláh would often go for a walk along the bank of the Tigris. He would come back looking very happy and write down those lyric gems of wise counsel which have brought help and healing to thousands of aching and troubled hearts. For years, only a few manuscript copies of the Hidden Words were in existence, and these had to be carefully concealed lest they should fall into the hands of the enemies that abounded, but now this little volume is probably the best known of all Bahá’u’lláh’s works, and is read in every quarter of the globe. The Book of Íqán is another well-known work of Bahá’u’lláh’s written about the same period, towards the end of His sojourn at Baghdád (1862–1863 A.D.)