...offered up, by his own hand, his life.

Consider his honor Siyyid Ismá’íl—upon him be the peace of God, and His loving-kindness—how, before daybreak he was wont to dust, with his own turban, the doorstep of My house, and in the end, whilst standing on the banks of the river, with his eyes fixed on that same house, offered up, by his own hand, his life.

-Baha'u'llah

http://reference.bahai.org/en/t/b/ESW/esw-4.html

One day, they brought the news of the death of Siyyid Ismá‘íl of Zavárih. Bahá’u’lláh said: ‘No one has killed him. Behind many myriad veils of light, we showed him a glimmer of our glory; he could not endure it and so he sacrificed himself.’ Some of us then went to the bank of the river and found the body of Siyyid Ismá‘íl lying there. He had cut his own throat with a razor which was still held in his hand. We removed the body and buried it.

(Revelation of Bahá’u’lláh, Vol 2, p. 112)