Rice has been on the radar for Chelsea and Manchester United in the last two transfer windows. However, the move has not materialized yet, and the Englishman is still at West Ham.
Speaking on Vibe with FIVE, Ferdinand urged his former side to retake a look at Rice. He said:
"That's not to say he hasn't got the ability, the kid's got ability, he's improving every single season you've seen him. He's added bits to his game. Last year, he added goals, the ability to drive with the ball from midfield.
He's defensively getting more acute and more understanding of the game, an absolute sponge of the game, educating himself all the time, always asking questions, always wants to know X, Y and Z. That's the type of player, the type of character that Man United need in their squad.
Forget ability sometimes, there might be players with more ability in that position than him, more technical maybe than him, but what he lacks in that area, which won't be by a lot, anything he lacks in that area he more than makes up for it in the other critical areas that United need most."
The Red Devils are actively looking to strengthen their squad, especially after the departures of Juan Mata and Paul Pogba. Barcelona's Frenkie de Jong is a name that has been associated with the club in recent times, however a deal is yet to be finalized.
West Ham not interested in selling Chelsea and Manchester United target
David Moyes has repeatedly insisted that Declan Rice will not be sold. He claims the Englishman is a vital part of their squad and that they are building a team around him.
Amid interest from Chelsea and Manchester United last season, he was quoted by Football London saying:
"The first thing to say is that he is not for sale. If you are interested, well, it will be north of that. £100m was cheap last summer. £150m just now would be the minimum but he is not for sale. What I do know is that it means there are only certain clubs that could even consider it."
Rice has reportedly rejected multiple contract offers from the Hammers and is keeping his options open.