The first Shabad of this Bani was written by Guru Arjan when he was separated from Guru Ram Das for a long period of time. During that period of separation he sent these three letters to his beloved Guru and Father. Reciting this shabad brings union of the beloved. The fourth shabad was added by Guru Arjan at the time of the union with Guru Ram Das.
In the turbulant times after Guru Arjun Dev Ji's martydom the Sikhs came to Guru Hargobind Sahib Ji (sixth Guru) and said "O Lord of all the heavens we are in turbulant times where we are preparing and training for battle which is cutting into our Naam/Simran time. Please tell us Sir, what prayers should we recite to make for this?" Guru Hargobind Sahib Ji answered that they should recite the shabads of Guru Arjun Dev Ji that he wrote to Guru Ram Das Ji.