By Bhakti Caitanya SwamiPrabhupada said that. Prabhupada said at the end of one class, to go back to Godhead you have to be 100% pure, all the devotees were like - me, 100% pure, don't know about that! And Prabhupada noticed and said, at least 90%. And devotees were still - leaves me out. Prabhupada said at least 80%. Still it was the same. And Prabhupada said just take hold of my dhoti and I will take you back, I have the key to the back door. (haribol)