How can I insert into laravel pivot table?

I have 3 tables:

stations (id,station_name) 
products (id,product_name)
product_station (station_id,product_id)

Station Model

protected $fillable = ['station_name'];
public function products(){
        return $this->belongsToMany(Product::class);
    }

Product Model

 protected $fillable = ['product_name'];

public function stations(){
    return $this->belongsToMany(Station::class);
}

I already have inserted stations and products and i want to insert station with it's own product using into Pivot table

AdminProductStationcontroller

public function create()
    {
        $station = Station::pluck('station_name','id')->all();

        $products = Product::pluck('product_name','id')->all();

        return view('admin.product_stations.create',compact('station','products'));
    }

I think there is error in store function below

    public function store(Request $request)
    {

        $station = new Station();

        $product = new Product();

        $station->save();

        $station->products()->attach($product);

        return redirect('/admin/product_stations');
     }

So i have got this error

(2/2) QueryException SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'product_id' cannot be null (SQL: insert into product_station (product_id, station_id) values (, 25))

via Chebli Mohamed