Query About Jetsun Milarepa Instruction on Bardo

I have come across a passage which reads:

རྗེ་བཙུན་མི་ལའི་གསུང་བགྲོས་བར་དོའི་དྲིས་ལན་གྱི་སྐོར་

I have only read portions of Jetsun Milarepa’s biography and songs. Does anyone know of a source text that this phrase might be referring to?

Thanks,

Art