Dennis Gartman has enjoyed decades of experience in the markets. But on Tuesday's episode of "Futures Now," he said there's only one lesson that truly matters.

"I've been at this 40 years, and I've learned one thing: Don't fight the Fed," Gartman said. "If you do, it's a losing battle. They have a bigger margin account than you or I will ever dream of having, and they're continuing to fund your margin account."

Because the Federal Reserve has the market's back, Gartman says it's foolhardy to fret about the fundamentals of the economy. Indeed, if the jobs report fails to meet expectations on Friday, he says it would actually be good news for stocks.

"If the numbers aren't good, you might get the stock market to take that very affirmatively, because they'll take that to mean the Fed will continue the process of quantitative easing, although at a lower pace," said Gartman, the editor of The Gartman Letter.

In a Monday speech, Federal Reserve Chair Janet Yellen said that the Fed's "extraordinary commitment" to improving the labor market is "still needed, and will be for some time." The dovish words indicated to investors that the Fed will not be quick to raise its ultralow federal funds rate target, which is a concern that cropped up during Yellen's press conference on March 19.

Read MoreYellen: Fed's 'extraordinary' policy to be around for the long haul

Traders took Yellen's more recent remarks quite favorably, as the rose sharply on Monday and hit a fresh all-time high on Tuesday.

At this point, Gartman's advice is simple.

"Here, write this down: The stock market will stop when it stops, and not a moment before. It's moving from the lower left to the upper right," Gartman said. "Enjoy the ride!"

—By CNBC's Alex Rosenberg. Follow him on Twitter: @CNBCAlex.

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