"We have heard"...
"I have heard the elders say"...
"As it has been said"
"We have heard" is shorthand for hearing and thinking a particular thing, but also humbly remaining open to more enlightenment and viewpoints.
Native Americans use this convention to speak to one another in a way that allows the listener to receive and evaluate the saying on its own merits. As opposed to a thinker saying "I think X", which can often be resisted / rejected almost subconsciously by the hearer.
Jesus also used similar tools to reference back to sayings the hearers would be familiar with, while illuminating new meanings and principles.