It is reported that Al-Sha’bī – Allāh have mercy on him – said:

Allāh the Exalted distinguished Abū Bakr Al-Ṣiddīq – Allāh be pleased with him – with four qualities He did not distinguish anyone else with: He called him Al-Ṣiddīq (the true believer), and He never named anyone else Al-Ṣiddīq; [Abū Bakr] was the companion of Allāh’s Messenger – praise and peace of Allāh be upon him – in the cave, and his companion during the Migration (Al-Hijrah); and Allāh’s Messenger – praise and peace of Allāh be upon him – told him to lead the prayer in the presence of the rest of the Muslims.

Abu Bakr Al-Daynūrī, Al-Mujālasah wa Jawāhir Al-‘Ilm article 2815.