Laravel HasMany RealtionShip Doesnot Work

Question

User Model

 public function teachers()
    {
        return $this->hasMany(Teacher::class);
    }

Teacher Model

 public function user(){
        return $this->belongsTo(User::class);
    }

TeacherController

 public function index()
    {
        $role_user = DB::table('roles')->where('role', 'teacher')->first();
        $role_id = $role_user->id;
        $users = User::all()->where('role_id',$role_id);


        return view('admin.teacher.index')
            ->with('users',$users);
    }

In View

 <td class="d-none d-sm-table-cell">{{dd( $teacher->teachers->designation)}}</td>

It Gives An Error like this
Property [designation] does not exist on this collection instance