Japanese Robin Hood

After Monday night zazen this evening, we read the following story from Book 1, Chapter 12 of Zuimonki:

Zen master Chikaku aroused bodhi-mind and became a monk. He had been a government officer. He was a man of talent and righteousness. While he was a provincial governor, he appropriated official money unlawfully and gave it to the people. One of the officers around him reported this to the emperor.

Upon hearing this, the emperor was astonished; all of his ministers also thought it strange. Still, since the crime was not a minor one, the decision was made to put him to death.

The emperor said, “This officer is a man of talent and a wise man. He dared to commit this crime. He might have had some profound motivation. When his head is about to be cut off, if he looks regretful and full of grief, cut it off quickly. If not, undoubtedly he had a deeper motivation, so do not kill him.”

When the Imperial envoy brought him out to cut off his head, he did not show regret or grief; rather he looked joyful. He said to himself, “I give this life to all living beings.”

The Imperial envoy, surprised and amazed, reported it to the emperor.

The emperor exclaimed, “It’s exactly as I thought! He must have had some deeper reason.”

When the emperor asked the officer what his motivation was, he said, “I wanted to retire from government office, throw my life away by giving it to all living beings to form an association with them, be born into the family of Buddha (become a monk), and practice the Buddha-Way whole-heartedly.”

The emperor was moved by his reply and allowed him to become a monk. Therefore, he was given the name Enju, meaning ‘prolonged life’, since he had been saved from capital punishment.

Commenting on this story, Dogen said, "Monks today also have to arouse aspiration like this at least once. Arousing such an aspiration means thinking little of your own life, having deep compassion for all living beings, and entrusting your bodily life to the Buddha’s teaching. If you have already aroused such aspiration, protect it; do not lose it even for a moment. It is impossible to realize buddha-dharma without arousing such aspiration."

One thing that interests me about this story is that I find it no place other than Zuimonki. It is not included in the Eihei Koroku ("Dogen's Extensive Record") nor have I come across it in the Shobogenzo. In Andy Ferguson's meticulously detailed "Zen's Chinese Heritage," there is are several pages of Zen Master Chikaku (Yongming Yanshou). Does anyone out there know anything more about this story? Are there any other commentaries?