IbÄ á Ä `` s agree with Sunnis in approving of AbÅ `` Bakr and Umar ibn al-Khattab , whom they regard as the two rightly-guided Caliphs . Ibadis agree with Sunnis in approving of Abu Bakr and Umar ibn al-Khattab , whom they regard as the two rightly-guided Caliphs .