Mullá Zaynul-ʻÁbidín (May 1818 − 1903) was a prominent Iranian Baháʼí who served as a secretary to Baháʼu'lláh, was listed by Shoghi Effendi as one of nineteen Apostles of Baháʼu'lláh, and biographied by ʻAbdu'l-Bahá in Memorials of the Faithful. With a background as an Islamic jurist, he posed the clarifying legal questions to Baháʼu'lláh about the Kitáb-i-Aqdas that became the supplement "Questions and Answers" now published along with the original text. His arrangement of the Hidden Words, another major work of Baháʼu'lláh, became the numbered order that is now currently used by Baháʼís.