Bahá'u'lláh completed the revelation of the Kitáb-i-Aqdas in the southeast corner room of the house of `Údí Khammár. [BBD132; BKG351; DH46; GPB213; RB3:275; SA248; BBS145]
• See A Description of the Kitáb-i-Aqdas by Shoghi Effendi.
• There is evidence to suggest that at least some of the work was written earlier as confirmed by the book's reference to the fall of Napoleon III in 1870 and there is further evidence to suggest that parts of the Kitáb-i-Aqdas were revealed as early as 1868. [SA16–17, 248]
• For the significance of the Kitáb-i-Aqdas see BKG351–3, BW15:87–91, GPB213–15 and RB3:275–399.
• For analyses of its significance, content and application, see RB3:275–399 and SA248–52.

The revelation of the obligatory prayers.

"Many of the laws of the Báb...are carefully designed in a way that testifies that the advent of Him Whom God shall make manifest was impending....The Báb never revealed the words of the (obligatory) prayer itself, thus making the implementation of this law dependent on the arrival of the Promised One." [GH366]

The original Bahá'í obligatory prayer, mentioned in the Kitab-i-Aqdas, involved nine cycles of movement starting with a bow (rak`ah) and was to be said morning, noon, and afternoon. It probably called for three rak`ahs at each time. Bahá'u'lláh revealed the text but did not release it in order to avoid provoking conflict with Muslims. (This prayer was one of the documents in the cases taken by `Abdu'l-Bahá's brothers shortly after the passing of Bahá'u'lláh.) Some time later, after the writing of the Kitab-i-Aqdas but before that of its supplement Questions and Answers, Bahá'u'lláh wrote a second set of obligatory prayers which are in use today. Three alternative forms were provided: a very short prayer to be said between noon and sunset; a somewhat longer prayer to be said in the morning, the afternoon, and the evening; and a long prayer to be said once during twenty-four hours. [Prayer and Worship by John Walbridge]

• See Entering into Obligatory Prayer: Introduction and Commentary by Ismael Velasco.
• See as well the message from the Universal House of Justice message of 28 November 2000 with commentary from Ismael Vlasco, Peter Terry and Michael Sours.

"When Bahá'u'lláh revealed the Kitáb-i-Aqdas He withheld the publication of certain laws. These included the text of the Obligatory Prayers. In one of His Tablets Bahá'u'lláh orders His amanuensis, Mírzá Áqá Ján, to send a copy of the Obligatory Prayers to Persia as a favour to Mullá 'Alí-Akbar who had asked for them. He confirms that the Obligatory Prayers had been revealed a few years earlier." [RoB4p299-300]
• (It) "was shared with Hand of the Cause Alí Akbar SháhMírzádeh Hajji Akhund in the Lawh-i Bishárát-i 'Uzma (Tablet of the Most Great Glad-tidings), and thus diffused among the community. [Kitáb-i-Aqdas: the Obligatory Prayers Notes by the Universal House of Justice, Ismael Velasco, Peter Terry, Michael Sours]
• See Kitáb-i-Aqdas: Tablet Study Outline .

The passing of Mullá Zaynu'l-'Ábidín, surnamed Zaynu'l-Muqarrabín (the Ornament of the Near Ones) in 'Akká. He is sometimes referred to as Jináb-i-Zayn (The Excellent Zayn), or Harfu'z-Zá (the Letter Z). He was born in the month of Rajab, in one of the villages of Najafábád near Isfahán to a family of Muslim clerics in May 1818. He had first heard of the Báb's claim while on pilgrimage in Karbilá in 1844 and became a believer in 1851. He met Bahá'u'lláh in Baghdád after His return from Kurdistán in 1856. He was among the believers who were exiled from Baghdád in July of 1868 and under his leadership and guidance the believers in Mosul became a model community. He was invited by Bahá'u'lláh to come to 'Akká in Sep-Oct 1885 and shortly after that Baha'u'lláh asked that the community in Mosul be abandoned. [EB274-276; MoF150-154; TN412-425]

Jináb-i-Zaynu'l-Muqarrabín was well versed in Islamic jurisprudence. After the revelation of the Kitáb-i-Aqdas, he was authorized to submit questions concerning the laws. The treatise, titled Questions and Answers, an appendix to the Kitáb-i-Aqdas, is a compilation he made of Bahá'u'lláh's answers to questions concerning the laws of the Most Holy Book. It took more than two decades for "Questions and Answers" to be published in Persian and much longer to be published in English and other languages. [KA9]

• See Some Answered Questions" and Its Compiler by Baharieh Rouhani Ma'ani published in Lights of Irfan, 18, pages 425-452. In this paper the author compares the similarities and differences of Questions and Answers and Some Answered Questions.
• For an image Zaynu'l-Muqarrabín see Picture Gallery (miniature by Ethel Rosenberg). This image can also been found in RoB1p78
• He was named as one of the Apostles of Bahá'u'lláh.

In a letter to an individual dated 23 February 2000 the Universal House of Justice commented on the way the new law was introduced for universal application.

For the proceedings see Law and International Order: Proceedings of the First European Bahá'í Conference on Law and International Order and for a review of the book by Joshua Lincoln see Bahá'í Library Online.

In a message from the Universal House of Justice addressed to the Bahá'ís of the world, some laws of the Kitáb-i-Aqdas which had not yet been universally applied were put into effect. Those were the laws that directly foster the devotional life of the individual and of the community which pertained to obligatory prayer, fasting and recitation of the Greatest Name ninety-five times a day.
"The friends have long been familiar with the great importance which Bahá’u’lláh attaches to daily obligatory prayer and to the observance of the fast, but a number of aspects of the law, such as those concerning ablutions, traveling and the compensation for prayers missed, remained to be made universally applicable. This step is now taken. Thus all elements of the laws dealing with obligatory prayer and fasting are, without any exception, now applicable."
• Those laws of the Kitáb-i-Aqdas that were not yet universally applicable were delineated in the message dated 8 February, 2001.

In a letter to an individual dated 23 February 2000 the Universal House of Justice described these three laws as "a matter of conscience" in that they are not enforceable as are the laws of marriage. They also point out that, unlike most laws, "genuine ignorance of a law is acceptable as an excuse for not adhering to it'.

The implementation of the Badí' Calendar on the first day of the tenth Váhid of the first Kull-i-Shay' of the Bahá'í Era.

"Báb introduced the calendar and its broad pattern of periods and cycles, months and days. Bahá'u'lláh provided essential clarifications and additions. Aspects were elucidated by 'Abdu'l-Bahá, and arrangements for its adoption in the West were put in place at the direction of Shoghi Effendi, as described in the volumes of The Bahá'í World. Still, ambiguities surrounding some Islamic and Gregorian dates, as well as difficulties in the correlation of historical observances and astronomical events with explicit statements in the Text, left certain issues unresolved. When responding to questions concerning the calendar, both 'Abdu'l-Bahá and Shoghi Effendi left these matters to the Universal House of Justice. Of its many features, three required clarification for the calendar's uniform application: the means for the determination of Naw-Rúz, the accommodation of the lunar character of the Twin Holy Birthdays within the solar year, and the fixing of the dates of the Holy Days within the Badí' calendar." [Message from the Universal House of Justice dated 10 July, 2014] (notes below extracted from the message)

The Festival of Naw-Rúz: The birthplace of the Abhá Beauty, will be the spot on the earth that will serve as the standard for determining, by means of astronomical computations from reliable sources, the moment of the vernal equinox in the northern hemisphere and thereby the day of Naw-Rúz for the Bahá'í world.

The Festivals of the Twin Birthdays: They will now be observed on the first and the second day following the occurrence of the eighth new moon after Naw-Rúz. This will result in the observance of the Twin Birthdays moving, year to year, within the months of Mashíyyat, 'Ilm, and Qudrat of the Badí' calendar, or from mid-October to mid-November according to the Gregorian calendar.

The dates of the Holy Days are: Naw-Rúz, 1 Bahá; the Festival of Riḍván, 13 Jalál to 5 Jamál; the Declaration of the Báb, 8 'Aẓamat; the Ascension of Bahá'u'lláh, 13 'Aẓamat; the Martyrdom of the Báb, 17 Raḥmat; the Day of the Covenant, 4 Qawl; and the Ascension of 'Abdu'l-Bahá, 6 Qawl. These dates have been fixed within the solar calendar in accordance with explicit statements of Bahá'u'lláh, 'Abdu'l-Bahá, and Shoghi Effendi. [Message from the Universal House of Justice dated 10 July, 2014]

• See Introduction to Badí' Calendar.