Open a page from a provider

Please, help me, it happens that I would like to open the Tabs page, given that it is my homepage and this.nav.push (TabsPage); it does not work for me any solution to launch the page from the provider?

   import { Injectable, ViewChild } from '@angular/core';
    import { ModalController, Nav } from 'ionic-angular'

//users provider
import { UsersProvider } from '../index.providers';

//pagina del login, esta sera mostrada como modal y la pagina de tabs
import { LoginPage, TabsPage } from '../../pages/index.pages';

@Injectable()
export class LoginProvider {


  constructor( private _us:UsersProvider, 
               private modalCtrl:ModalController
                ) {
  }

  //ESTA FUNCION SE EJECUTA SI TODO ESTA VALIDO PARA MOSTRAR LA APP
  entrar_app(){

    let modal:any;

    //SI EXISTE TOKEN
    if(this._us.token){

      //mostrar app
       this.nav.push(TabsPage);

    }else{
      //mostrar login
      modal = this.modalCtrl.create(LoginPage);
      modal.present();
    }

    modal.onDidDismiss( (open_app:boolean)=>{

       if( open_app ){
            this.nav.push(TabsPage);
       }

    })

  }

}