There is a universally-accepted custom amongst Jewish communities to recite Psalm 27 "The Lord is my light and my salvation" twice a day from the beginning of the month of Elul until until Shmini Atzetet.
This Psalm has two parts, with each one having its own distinct theme. At the beginning of the Psalm, the poet creates the impression that his trust in God causes him to be unafraid. "When evildoers draw near to me … they stumbled and fell" and even more so "If a camp encamps against me, my heart shall not fear."
