Wow, that's not clear at all. I've got no idea. I'll send out some feelers.
It's a paraphrase of Gen. 49:22-23. It says:
יוסף בן פורת עלי עין בנות צעדה עלי שור וימררוהו ורובו וישטמוהו
Which isn't all the words from those verses, but it's most of them.