BABAK (d. 1642), a Muslim rababi or musician, kept Guru Hargobind company and recited the sacred hymns at divans morning and evening. The word babak, from Persian, means faithful. As says the Gurbilas Chhevin Patshahi, Babak was, at the death of Satta and Balvand, who used to recite sacred hymns for the Guru, asked to perform the obsequies for them under their (Muslim) rites. Babak, it is said, dug the graves for the deceased on the bank of the River Ravi and after the burial service, performed the kirtan on the site where sat Guru Hargobind. 

To quote the Gurbilas again, he took part in the battle of Amritsar in 1629 during which he assisted in the evacuation of the Guru\’s family to Jhabal. Going by the Gurbilas account, Guru Hargobind, before he departed the world, asked Babak to return to Amritsar. As bidden by the Guru, Babak retired to Amritsar where he died in 1642.

References :

1. Gurbilas Chhevin Patshahi. Patiala, 1970
2. Gian Singh, Giani, Twarikh Guru Khalsa. Patiala, 1970
3. Macauliffe, M. A., The Sikh Religion. Oxford, 1909