The reference is to Exodus 4:24-26. No one knows what it means. It's not even clear who is doing what. Did YHWH try to kill Moses or his son? Did Zipporah touch Moses or her son or YHWH with the foreskin? And the big question for what everyone does is: Why?
The interpretation in this essay has the merit of being original.
For more on Zipporah, see here (immediately preceding post).
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