The Kitáb-i-ʻAhd (Arabic: ﻛﺘﺎﺏ ﻋﻬﺪﻱ literally "Book of My Covenant") is the Will and Testament of Baháʼu'lláh, the founder of the Baháʼí Faith, where he selects his son ʻAbdu'l-Bahá as his successor.
[1] An English translation is included in the Tablets of Baháʼu'lláh Revealed After the Kitáb-i-Aqdas, published in 1978.
While the Tablet of the Branch, composed in the Adrianople period had clearly signaled a high station for "the Branch of Holiness" and the Kitáb-i-Aqdas has specified that this high station involved leadership of the Baháʼí community after Baháʼu'lláh's passing, it was only with the unsealing of the Kitáb-i-ʻAhd after the passing of Baháʼu'lláh in 1892 that it was confirmed that the Branch referred to was indeed ʻAbdu'l-Bahá.
[3] Baháʼu'lláh designates his successor with the following verses: The Will of the divine Testator is this: It is incumbent upon the Aghsán, the Afnán and My Kindred to turn, one and all, their faces towards the Most Mighty Branch.
The object of this sacred verse is none other except the Most Mighty Branch [ʻAbdu'l-Bahá].