Baba Farid Ganj-i-Shakar was a Chishti Sufi of the twelfth and thirteenth centuries, born at Kothewal near Multan, who settled at Ajodhan, now Pakpattan. His 134 shloks and four hymns are in the Guru Granth Sahib Ji.
He is the earliest Punjabi writer whose work survives. Punjabi literature begins with him, and it begins in the mouth of a Muslim saint whose verse was preserved by Sikhs.
His shloks are about the body failing, birds on a dead tree, the shortness of the thread. They are the plainest Punjabi in the volume and the closest to ordinary speech.
Guru Nanak Dev Ji visited Pakpattan and met his successor. The compositions came into Sikh hands through that line of transmission, which is why the Guru Granth Sahib Ji holds a Chishti corpus that no Sufi shrine preserved as completely.
The Behesht Darwaza at his shrine at Pakpattan is opened once a year and hundreds of thousands pass through it. In 2001 a crush at the gate killed dozens.
His shlokas and hymns in the Guru Granth Sahib Ji are the oldest Punjabi in the volume and among the oldest surviving Punjabi of any kind.
The language is plain and the subject is mortality, restraint and the treatment of others, and several of the shlokas are proverbs in ordinary Punjabi speech now without anybody knowing where they came from.
Whether the compositions are the twelfth century Farid's or a later successor's at Pakpattan is argued. What is not argued is that the Punjabi language's written history begins with them.