David Moyes thinks Manchester United should stand by Louis van Gaal and claims the club would be setting a dangerous precedent if they sacked the Dutchman.
Van Gaal is under pressure after his United team embarked upon their worst run in 26 years.
United have dropped out of the top four in the Barclays Premier League and were eliminated from the Champions League following a run of eight matches without victory.
After 26 years of stability under Sir Alex Ferguson, United sacked his successor Moyes after just 10 months in charge.
Dismissing Van Gaal 18 months into his reign would be a step in the wrong direction and dent the club's credibility, according to Moyes.
"I think what Manchester United stand for is that they keep their managers, they've always supported their managers," Moyes told the Clare Balding Show on BT Sport 1.
"I hope they stick with Louis van Gaal, he deserves more time. It's still a work in progress for him, he's made some signings and from my experience in Spain it will take time for players from abroad to settle in. So, I think they should stick with it. They don't want to become a club which continuously changes their manager."
Ferguson won 38 trophies during his successful spell as the club's manager, but the season after he left, United ended the year in seventh after sacking Moyes.
In Van Gaal's first season, United qualified for the Champions League, but they are now five points off the top four at the half way stage.
Moyes admits life after the most successful manager in the club's history was never going to be easy.
"I think after Sir Alex the job was going to be very difficult," the Scot said.
"It was going to take time to rebuild, it was a rebuilding job at Manchester United. You've got to remember (former chief executive) David Gill left (at the same time as Ferguson), he was a big influence at Manchester United."
And 16 months on, it is clear the former Everton manager is still unhappy about how his reign at Old Trafford ended.
"My understanding was that I was going to a club which always looked after their managers, even when they were in trouble and it wasn't going well, you got your time to sort things out," Moyes said.
"I was under that illusion when I was there. I had a great group of players they had recently won the Premier League under Sir Alex, but it was going to take time for that to change, evolve and of course there was going to have to be a changeover of players in time, but it couldn't be done in 10 months."
Moyes, who was sacked by Real Sociedad last month, insists he would take the position at Old Trafford again, however.
He added: "Of course I would. There are very few managers in the world who wouldn't want to manage Manchester United."
The 52-year-old gave his backing to Wayne Rooney, who has scored two league goals this season.
Moyes thinks Rooney is still good enough to lead the line for the team, but believes his long-term future lies in midfield.
"H e is having a tough time, but I think he will come through it," said Moyes, who handed Rooney his Everton debut in 2002.
"I have always said he will be a midfield player and he will come again, but at the moment he is such a good goalscorer, you don't want to give it up just yet."