The Reason for being Given the Title Al-‘Ateeq:
Hazrat ‘Abdullah bin Zubair (radhiyallahu ‘anhu) reports that on one occasion, Rasulullah (sallallahu ‘alaihi wasallam) turned his mubaarak gaze towards Hazrat Abu Bakr (radhiyallahu ‘anhu) and mentioned:
هذا عتيق الله من النار
This person (Hazrat Abu Bakr (radhiyallahu ‘anhu)) has been granted emancipation from the fire of Jahannum by Allah Ta‘ala
It was on that occasion that Hazrat Abu Bakr (radhiyallahu ‘anhu) received the title ‘Ateeq.
(Majma‘uz Zawaa’id #14289)