Two aspects underline the precedence of Abū Bakr al-Ṣiddīq.
Companionship with the Prophet ﷺ: His distinguished association with the Prophet is acknowledged, and the Qur’an refers to him as a “companion” (ṣāḥib). That special companionship is central to his merit.
Precedence in leadership: He is the first among the Rightly Guided Caliphs. He is thus recognized as having precedence in merit and in succession.