DUP leader Arlene Foster has wished a speedy recovery for Martin McGuinness “despite all that has happened”.
The former deputy first minister announced on Thursday that he was quitting politics due to illness.
Mrs Foster spoke of her determination to work with Mr McGuinness when she became Northern Ireland’s first minister last year.
She said: “Martin McGuinness and I have had our political differences and we come from very different angles of vision.
“When I was elected as first minister in January 2016 I indicated that alongside him I was determined to work with him for the betterment of all the people of Northern Ireland in order to build a better future for everyone.
“While the current political situation is not what any of us would wish and there is much work to be done to return stable government to Northern Ireland, I nonetheless value the good things achieved by the outgoing Executive and the contribution made by Mr McGuinness to it.
“As deputy first minister for almost a decade Martin McGuinness has been a major figure at Stormont. While never forgetting the past I believe the work at Stormont provided the foundations for our relative peace today.”
She added: “Despite all that has happened I wish Martin McGuinness a speedy recovery and that he and his wife are able to enjoy time with their family away from the relentless focus of public life.”
Sinn Féin president Gerry Adams, meanwhile, said his “comrade” has been responding well to treatment and still hopes to play a role in the “process to end partition”.
He added: “I also want to thank Bernie and the entire McGuinness family for the support they have given to Martin over many years and for allowing him to become the leader, the patriot, the peacemaker and poet that he is.”
Alliance leader Naomi Long said: “Whilst our politics are very different, I recognise the degree to which he stretched himself and his constituency over recent years in order to move the political process forward.”