Another problem is replacing the Word of God with teachings from certain rabbis, pastors, theologians or other "experts". That was the status quo during Jesus's ministry, and such personality cults are still prevailing in some orthodox Jewish communities in Israel. In the Sermon on the Mount, all those "you've heard it's said" were references of such teachings from some prominent rabbis. At the end, the audience were "astonished", not entirely by the contents of the sermon, but by his audacity to challenge the rabbis, his critical thinking skills, as he spoke with AUTHORITY instead of quoting this or that rabbi like most speakers usually did.