Tillerson, in a message sent to US embassies and consulates three days after President
Donald Trump ousted him, also told American diplomats he was proud of them and would be cheering for their success.
"Know that I will continue to pray for our country, our leaders, and your efforts to make this world a better place than we found it,"
Tillerson said Friday in the message, a copy of which was obtained by The Associated Press.
He urged the diplomatic corps to "continue to exhibit the leadership qualities for which you are distinguished" as they prepare for new leadership.
Tillerson, whom Trump unceremoniously fired Tuesday, did not mention the president or his designated successor, CIA Director
Mike Pompeo, in the message. But he said the State Department was "in good hands" with its interim chief, Deputy Secretary of State
John Sullivan.
"In this time of transition, I know you will continue to exhibit the leadership qualities for which you are distinguished," he said. "I urge you to remain focused on our shared mission and embrace an orderly and smooth transition process. I have every confidence that you will continue to work diligently to advance our national interests and our values as a nation."
Tillerson was widely criticized for trying to slash the State Department's budget and staffing, sending morale plummeting. Nevertheless, he praised the diplomatic corps for their dedication, talent and patriotism as well as their willingness to serve the nation far from home and often at personal risk.
"Although you typically receive little recognition or acclaim for these sacrifices, your uncommon devotion allows hundreds of millions of Americans to live in peace and in freedom," he said.
Tillerson has relinquished day-to-day responsibilities of the State Department to Sullivan but will continue to hold the secretary of state title until March 31.
Tillerson, who had been seen as a restraining influence on Trump, had clashed with the president over numerous foreign policy matters, including the Paris Climate Accord, the relocation of the US embassy in Israel from Tel Aviv to Jerusalem, and the Iran nuclear deal.
After months of speculation about his future in the administration, Trump fired Tillerson just hours after the secretary of state had returned to Washington from a five-nation tour of Africa.
