The 19-year-old has been heavily linked with a move to Old Trafford after a superb breakthrough season in the Bundesliga in 2018/19.
Sancho scored 12 league goals and provided 14 assists for Dortmund as they finished runners-up to Bayern Munich.
Rooney, who now plays for DC United in Major League Soccer, told German newspaper BILD that his compatriot’s development would be best served by continuing to get regular game time at Signal Iduna Park.
"Dortmund is a great club with great fans, they trust their young players, and you can see that in Sancho and the progress he has made in the last 12 months,” said Rooney.
"Now Jadon has to ask himself whether he would get the playing time he gets in Dortmund when he moves to England, or would he just sit on the bench?
"Playing time is so important for a young player like Jadon, so if he gets the most playing time in Dortmund, he should stay there."
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