"Unto everyone hath been enjoined the writing of a will"

Unto everyone hath been enjoined the writing of a will. The testator should head this document with the adornment of the Most Great Name, bear witness therein unto the oneness of God in the Dayspring of His Revelation, and make mention, as he may wish, of that which is praiseworthy, so that it may be a testimony for him in the kingdoms of Revelation and Creation and a treasure with his Lord, the Supreme Protector, the Faithful.

Baha'u'llah, The Most Holy Book, Paragraph 109 

The same verse was provided in an earlier translation by the Universal House of Justice:

"In the 'Kitáb-i-Aqdas' Bahá'u'lláh has stated:

'It is incumbent upon every one to write his testament. It behoveth him to adorn its heading with the Most Great Name, to testify therein to the oneness of God as manifested in the Day-Spring of His revelation and to set forth such good deeds as he may wish to be realized, that these may stand as his testimony in the worlds of Revelation and of Creation and be as a treasure stored up with his Lord, the Protector, the Trusted one'."

(From a letter written on behalf of the Universal House of Justice to a National Spiritual Assembly, September 4, 1982; Lights of Guidance, 2nd edition, p. 192, #630)