Isra and Mi'raj
In Arabic, the name "Abd Allah" means "servant of Allah". One of his early titles, preceding his conversion to Islam, was "Ateeq", meaning "saved one". Muhammad later restated this title when he said that Abu Bakr is the "Ateeq". He was called "Al-Siddiq" (the truthful) by Muhammad after he believed him in the event of Isra and Mi'raj when other people didn't, and Ali confirmed that title several times. He was also reportedly referred to in the Quran as the "second of the two in the cave" in reference to the event of hijra, where with Muhammad he hid in the cave in Jabal Thawr from the Meccan party that was sent after them.