Welbeck was sold to Arsenal on deadline day.
"Obviously time will tell (if he prospers at Arsenal)," Rooney told BBC Radio Five Live of his England team-mate. "It is obviously a good move for Danny.
"It was difficult because he wasn't playing all of the time at Manchester United, so he had to make a decision and he has obviously chosen to leave.
"We will miss him in our dressing room. He is a great friend of mine, he was great around the dressing room, so we will miss him, but I wish him all the best."
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