Where did the Buddha say that the minor rules for monks could be ignored?

In his lecture course Sacred Texts of the World , Grant Hardy said that the Buddha had instructed that the minor rules for monks could be ignored. However the Buddha didn't say which rules he considered minor so when the Vinaya was being compiled all the rules were included just to be sure. I find this intriguing. Does anyone know where the Buddha said this - is there a reference in the Pali Canon or elsewhere about this. I believe this happened near to the Buddha's death so it could be one of the sutras about his paranirvana. Also, within the Vinaya or commentaries is there any indications about which rules are considered minor or of lesser importance that the others. Did any of the Buddha's intention in this matter make it into the texts - assuming that Grant Hardy is accurate in this issue.