Want a passing game to try first?
A five-minute rally where the ball keeps moving and every pass counts toward one shared number.
See the passing gameSome children never let go of the ball. It's rarely bad manners.
When a child will not pass the ball and hogs it, the game you're playing is usually the thing to change first, not the child.
Two changes fix it without a lecture. Score team points so a pass earns more than a solo run, and give the dribbler a touch limit so releasing the ball is the easy choice. The FA's own guidance for 5 to 11s treats staying on the ball as a skill and warns against telling children to always pass early, so the aim is to make passing worth it, rather than to ban dribbling.
I used to shout "pass it!" from the patio every thirty seconds, and the ball went on doing exactly what it had been doing.

It usually makes sense to them
A kid who always keeps the ball to themselves in football is usually reacting sensibly to the game in front of them. In a game of two or three, the ball is the fun. Passing it away means standing still and waiting for it to come back, and a shout of "pass!" gives no reason to do it.
Dribbling is also how they are learning. Every touch is practice, and nobody gives that up because a grown-up is cross about it from the patio.
There is one more thing to check before blaming them. I had never once passed it back to mine in a way that made giving it up worth it, since I was usually the one dribbling round in circles. A grown-up who never plays the ball back is teaching exactly the same lesson.
Score it as one team
Play as one team at a goal made of two markers, with you and your child together, or your child and a sibling. A goal scores 1 point. Each pass before it adds 1 point, up to 3 points a goal.
The arithmetic. Solo dribble and goal: 1 point. Goal after one pass: 2 points. Goal after two passes: 3 points, the most a goal can score.
Now the child is no longer racing you, so hogging costs points instead of winning them, and nobody has been told off. A pass actually pays.
For the first few goes, play the ball straight back every time. Giving the ball away should never mean losing it, so the first passes feel safe rather than risky.
A cap on the dribbler
This game has goals and puts a cap on the dribbler. For a rally with no goals, the passing without stopping game is the step to try.
Two markers for a goal. Set two jumpers or cones a couple of big strides apart at one end of the lawn, side-on to the fence and the hedge.
A touch limit for everyone. Start at five touches before the ball has to be passed or shot. Drop to three once that feels easy, then to two.
Count the touches. Say them out loud up to the limit, "one, two, three, four, five, pass", so the limit is a game and not a telling-off.
Grown-up obeys it too. The limit applies to you as well. That fairness is what makes it feel like a game and not a punishment.
Score it as one team, exactly as in the team points game: you and your child are on the same side, and a goal is worth 1 point plus 1 for each pass before it. If the ball goes past the limit, that attempt scores nothing. It is a free restart from the start spot, with no fuss and no comment. Once passes are happening, the one-two passing game is where to go next.

What the guidance says
The FA's guidance for 5 to 11s says "Staying on the ball is about the player knowing they can keep the ball for longer." It also warns against telling players to always pass the ball early to the easiest option, and says that "For younger players, managing the ball might be all they can cope with. And that's okay." Read the England Football guidance on skills on the ball.
This is coaching guidance from a governing body, not a controlled study, so it has no sample or measured effect. It is written for coaches of groups rather than one child in a garden, and it does not mention a child who refuses to pass at all, so it backs the reframe without proving these two games will change any one child.
If nothing shifts on the first night
Give it three or four goes at each limit before deciding anything. A script for the start: "Shall we play team points, you and me on the same team?" And one for the moment of the hog: "Nice run. Want to see what two of us can score?"
Keep praise on the pass ("that pass made three") rather than the passer. If a sibling is the one getting upset, the managing siblings guide has the jobs and handicaps that fit, and what to say during play has words that keep it light.
Some children will still choose to dribble, and at this age that is allowed to be part of the game.
Quick answers
Usually because holding the ball is the fun part and a pass gives them nothing back. The FA's guidance for 5 to 11s treats staying on the ball as a skill, and says that for younger players managing the ball may be all they can cope with.
It rarely works, because a shout gives no reason. The FA guidance warns against telling players to always pass early to the easiest option. Change the scoring so a pass earns more, then praise the pass.
Play as one team, score 1 for a goal plus 1 for each pass before it (up to 3), and use a touch limit of five, then three, then two touches, applying it to yourself too.
Not on this evidence. A child who dribbles a lot is often just enjoying the ball, and a game with a shared score gives them a reason to share it without being told off.
Keep going
Three places to go next, depending on what you are working on. And choosing a position for your child can help the ball-hog find a role.
A five-minute rally where the ball keeps moving and every pass counts toward one shared number.
See the passing gameFixed jobs and small handicaps that keep both children in the same game.
See the siblings guidePass, move to a new spot and get it played straight back.
See the one-two gameTonight's five minutes
Two markers, one ball, one shared score. Return every pass for the first few goes.