The search for this specific title primarily yields fan-made . It is likely you are looking for one of the following:
An original Müslüm Gürses solo track released in 2000 on the album Zavallım . Muslum Gurses Feat Gazapizm Bir Gun
A popular unofficial mashup combining Müslüm Gürses' classic "Bir Bilebilsen" with Gazapizm's verses, widely available on platforms like SoundCloud . The search for this specific title primarily yields fan-made
Müslüm Gürses passed away in 2013, so any "new" releases featuring contemporary rappers like Gazapizm are typically posthumous mixes created by DJs or producers. Bir Gün Yalnız Kalırsan Muslum Gurses Feat Gazapizm Bir Gun
There is no official collaboration titled "Bir Gün" by featuring Gazapizm .