The battle for post-Brexit Britain will not be won by a "paranoid political movement", First Minister Carwyn Jones has said.
Writing for the Sunday Times after the re-election of Labour leader Jeremy Corbyn, Mr Jones said trolling and threats within Labour had to "stop".
But he said Labour rebels would be awarded "no prizes" for sulking.
He reiterated the message in his speech at the Labour party conference in Liverpool on Sunday.
In his letter to the Sunday Times, the first minister wrote that Jeremy Corbyn's second win "gives us all some certainty in uncertain times. Every Labour Party member now has a responsibility to show our best selves to the rest of the country".
He said: "The battle for the soul of post-Brexit Britain won't be won by a paranoid political movement more concerned with rooting out 'traitors' than it is with the economy, security and happiness of our country.
"The booing, the hissing, the name-calling, the trolling, the threats… it has to stop.
"In what world are we living in, when the Labour party has to commission a report into anti-Semitism in our own party?"
Mr Jones said there needed to be "recognition now that no battle of ideas can ever be truly won, that challenge and difference can be channelled into a successful and united party".
"It needs some give and take. Just as those of us who campaigned for Remain will be awarded no prizes for sulking post-Brexit, those who challenged Jeremy will be awarded no prizes for sulking after this weekend," he said.
"It is time to get on with it."
In a speech to the conference on Sunday, Mr Jones again urged Labour members to put aside their differences and unite.
"We have no hope of creating an open, tolerant country if we cannot first do the same for our own party. If we really want to shape what post-Brexit Britain looks like, we have to start treating one another with respect," he said.
"None of us want to live through any more bitter days for the Labour Party. The only threat we should present is to the Conservative government."
He also spoke of Labour's record in government in Wales and outlined details of its five-year plan.
In the Sunday Times article, Mr Jones also revealed UKIP and the Tories would attend a Welsh Government Brexit advisory group.
He said at the first meeting next week, "sitting around that table, in addition to people from business, academia and civic life, will be representatives of Welsh Labour, the Conservatives, Plaid Cymru, the Liberal Democrats and yes, UKIP too".
It is not clear who will represent each parties on the group but a Welsh Government announcement is expected next week.
The Welsh Government had previously said the group would be made up of "business people, politicians and experts with a detailed understanding of the European Union" but would not reveal any names at the time.