The Guru Granth Sahib Ji opens with a numeral. ੧ and then ਓਅੰਕਾਰ. Ik Onkar, one being.
The rest runs: true is the name, the doer, without fear, without enmity, timeless in form, unborn, self-existent, known by the Guru's grace.
It is repeated in full or in shortened form at the head of sections throughout the volume, over five hundred times, which makes it the most frequently written passage in the scripture.
The first character is a digit, not a letter. Beginning a religious text with the number one rather than a word is a deliberate choice and it is doing the same work as the four doors of the Harmandir.
It is recited by children learning to read Gurmukhi as their first sentence, and by adults at the start of the Japji Sahib every morning.
Ik Onkar is one, and the sound. The numeral is unambiguous in a way a word is not. It cannot be declined, cannot be made plural, and cannot be read as a name.
The line opens the Japji and it is also the standing definition placed at the head of the whole volume, so that everything after it is read under it.
It is the most reproduced piece of Gurmukhi in the world, on buildings, on vehicles, on jewellery and on the walls of houses in every country Punjabis have settled in.