HuffPo has an email which Sen. Sanders has sent to ~100 of his supporters last night. You can read the whole thing via this link; here’s some key grafs:
As surrogates who will be speaking on behalf of our campaign on television, radio, in newspapers and on social media we must never forget what this campaign is about and who our real opponents are. They are the most dangerous president in modern American history and the powerful special interests who back his agenda.
As we engage with our opponents in the Democratic primary, we will forcefully present our views and defend ourselves against misrepresentations. But, let us do our very best to engage respectfully with our Democratic opponents - talking about the issues we are fighting for, not about personalities or past grievances. I want to be clear that I condemn bullying and harassment of any kind and in any space.
Remember that our struggle is bigger than a Tweet or a Facebook comment. And remember that our primary opponents are decent people – many have been friends and allies of mine in the Senate.
Our number one priority is defeating Donald Trump. To do so, we will ultimately have to unite with those who today are our opponents for the Democratic nomination. We won’t always agree with them, but I expect those who speak on behalf of my campaign to always engage respectfully.
I am committed to making this nominating process a fair, issues-focused campaign and am asking you for the same.
I think that’s wise counsel for all of us in all forums — whether campaign surrogates or merely enthusiastic supporters, whether here or on tv or in talking to friends. Let’s never forget who our real opponents are—they are not other Democrats running in this presidential primary.