Some people say kaza does not exist. It is bidat to make kaza namaaz. How true is this? Do we have any prrof for that?

Answer

Yes, it does exit, as Nabi (Sallallaahu alaihi wasallam) himself performed it at the occasion of the battle of Ahzaab. And on another occasion Nabi (Sallallaahu alaihi wasallam) and the Sahaba (Radhiyallaahu anhum) missed fajr swalaat and they replaced it after sunrise.