hasOne() not returning relationships because of method name

I am using laravel 5.3, I have listings table with hasOne relationship to cities table.

public function city()
{
    return $this->hasOne('App\City', 'id', 'city_id');
}

on my view

this cause error

Trying to get property of non-object

But when I change the method name to other than city,

public function foo()
{
    return $this->hasOne('App\City', 'id', 'city_id');
}

on my view

This one works.

What cause the problem with city method name? I have never problem with city method name in other projects.

via Chebli Mohamed