Ahead of Sunday's services for murdered officer Wenjian Liu, NYPD Commissioner Bill Bratton sent a clear message to members of his department on Friday: "A hero's funeral is about grieving, not grievance."

That's how Bratton began a memo urging police not to use the event as a venue for protest, as many had last weekend when they turned their backs to Mayor Bill de Blasio at the funeral of slain officer Rafael Ramos.

"The city's and the country's consciousness of that funeral has focused on an act of disrespect," wrote Bratton. "It was not all the officers, and it was not disrespect directed at Detective Ramos. But all officers were painted by it, and it stole the valor, honor, and attention that rightfully belonged to the memory of Detective Rafael Ramos."

Bratton emphasized that his plea was not a mandate and that he was not threatening to discipline officers, but wished to "remind" them that "when you don the uniform of this department, you are bound by the tradition, honor, and decency that go with it."

Below, via the New York Post, is Bratton's memo in full:

TO: All Commands, All Members

RE: Comportment at the Funeral of Detective First Grade Wenjian Liu

A hero's funeral is about grieving, not grievance.

Last Saturday, the New York City Police Department buried a hero. Tens of thousands of officers from our department and hundreds of other departments came to show respect for Detective First Grade Rafael Ramos. His family witnessed the kind of love that only his second family in blue could display. But for the last seven days, the city's and the country's consciousness of that funeral has focused on an act of disrespect shown by a portion of those tens of thousands of officers. It was not all the officers, and it was not disrespect directed at Detective Ramos. But all officers were painted by it, and it stole the valor, honor, and attention that rightfully belonged to the memory of Detective Rafael Ramos's life and sacrifice. That was not the intent, I know. But it was the result.

On Sunday, we will gather together again, with the rest of New York City and law enforcement officials nationwide, to mourn for Detective First Grade Wenjian Liu. We gather to support his parents, his widow, and everyone who is there to remember a life tragically cut short.

The assassination of Detectives Liu and Ramos was an attack on us all. As a cop, one who lived and worked through the assassination threats of the 1970s, I understand that emotions are high. I issue no mandates, and I make no threats of discipline. But I remind you that when you don the uniform of this department, you are bound by the tradition, honor, and decency that go with it.

William J. Bratton

Police Commissioner

**To be read and/or viewed and displayed at all roll calls on Friday January 2, Saturday January 3, and Sunday January 4**

[Image via AP Images]