Washington (CNN) Outgoing Secretary of State Rex Tillerson called Washington a "very mean-spirited town" in his goodbye address to State Department staff on Thursday.

"This can be a very mean spirited town," Tillerson said, as staff present at his remarks laughed and clapped.

"But you don't have to choose to participate in that," he added.

In Tillerson's brief speech ahead of his official departure at the end of the month, he told State Department employees to hold on to their integrity. "It belongs to you," Tillerson said. "Only you can relinquish it or allow it to be compromised."

President Donald Trump announced the firing of Tillerson last week by tweet and named CIA Director Mike Pompeo, who a faces Senate confirmation hearing tentatively set for April 12, as his successor.

Tillerson's tenure was marked by plummeting morale and multiple vacancies in important posts, as the Trump administration moved to slash the agency's budget and move decision making on many high-profile issues to the Pentagon or the White House.

But the 69th Secretary of State got sustained applause from staff, who clapped solidly for many minutes after Tillerson finished his remarks and while he slowly worked his way toward the exit, shaking dozens of hands as he departed. State Department officials say he was leaving directly for Texas.

Tillerson mentioned Trump only once in his remarks, in passing and not by name, as he told staffers about preparing background materials "that were first the basis for discussions at the National Security Council and ultimately with the President."

Tillerson said he'd prepared those materials for Pompeo so he would be able to see the basis for the strategy and tactics which guided the department on the major foreign policy issues.

"The country faces many challenges -- in some instances perplexing foreign affairs relationships, and in other instances serious national security threats," Tillerson told a crowd of several hundred gathered in the State Department's main entrance and on balconies overlooking it. "In these times, your continued diligence and devotion to the State Department's mission has never been more necessary."

The crowd listened quietly until Tillerson ventured into more personal territory, and touched on themes that he had revisited more than once during his tenure. Foreign service officers and civil servants burst into laughter and applause, with many nodding, after Tillerson observed that Washington can be a mean-spirited place. When he followed that up with the advice that people don't have to participate "in that," he was again interrupted by clapping.

"I'd like to ask that each of you undertake to ensure one act of kindness each day towards another person," Tillerson said. And he called on employees to "treat each other with respect," adding that "we're all just human beings trying to do our part."

"Each of us get to choose the person we want to be, and the way we want to be treated, and the way we will treat others," he said.

The former ExxonMobil CEO's leadership at State was characterized by often public friction with the White House and the President himself over staffing and policy.

Trump very publicly took a different stance than his secretary of state on a dispute between Gulf nations, publicly mocked Tillerson's diplomatic efforts with North Korea, and disagreed with his top diplomat on how to approach Iran.

And, as with his call to State Department staffers to treat each other with respect, Tillerson repeatedly appeared to distance himself from the President on issues of behavior and the treatment of others.

In the wake of the President's comments that there were "good people" among white supremacists rallying in Charlottesville, after a woman was killed by one, Tillerson delivered a speech at the State Department about the importance of integrity.

After Trump dismissed African countries as "shitholes" in remarks to lawmakers, Tillerson spoke about the importance of inclusiveness, diversity and respect.

As the #MeToo movement about sexual harassment gathered steam, Trump defended a White House employee who was terminated after an alleged history of wife beating, and said, that "people's lives are being shattered" by "a mere allegation."

Days later, Tillerson addressed State Department employees about the need to intervene if they see sexual harassment and report it.