"Tablet explaining this existed but had been stolen by Covenant-breakers."

The obligatory prayer should be said facing the qiblih (point of adoration, i.e. the direction to face in prayer). The Báb had specified that in prayer believers should face Him Whom God shall make manifest. Thus during His lifetime Bahá'ís prayed facing the person of Bahá'u'lláh. `Abdu'l-Bahá later explained that after Bahá'u'lláh's death, the qiblih was Bahá'u'lláh's shrine and that a Tablet explaining this existed but had been stolen by Covenant-breakers. Facing the qiblih is obligatory for all three obligatory prayers.

John Walbridge, 1950. "Sacred Acts, Sacred Space, Sacred Time." Baha'i Studies 1996


Three days after the ascension of Baha’u’llah, Mirza Muhammad-‘Ali asked me to give him the keys so that he might open the cases. He said: “Baha’u’llah has placed a certain document in these cases which needs to be studied.’ He took the keys from me. The next thing I noticed was that with the help of Majdu’d-Din, ‘Ali Rida, his sister, and the mother of Shu‘a‘u’llah the cases were taken out of the window onto the balcony of the mansion and from there into the room of Mirza Muhammad-‘Ali. He took out all the Tablets of Baha’u’llah...

Shahin Vafai, The Essence of the Covenant - Features, History, and Implications