The first six handfuls of grain were handed over in exchange for a new ox! Leveraging social networking platforms into effective conduits for your personal brand is all about building word of mouth. There’s nothing new in that. Since the first six handfuls of grain were handed over in exchange for a new ox, business owners have always known that what their customers and their friends, family, or colleagues think about their restaurant or car or vacation spot or cleaning service or design firm has always mattered more than any billboard or radio ad they could buy. What does "the first six handfuls of grain were handed over in exchange for a new ox" mean here? Is it an idiom? Thanks a lot in advance