Asslamoalikum dear friends i want to ask that my father fasts but he sometimes shows laziness and does his prayers as Qaza. he goes to pray magrib prayer and does rest of them all as qaza at that time. is his fast eligable? will ALLAH accept his fasts ?
No one can certainly say if even a praying persons fast is accepted. This is between the person and Allah.
But the purpose of fasting is to gain taqwa and fear of crossing Allah's prohibitions. So it's a fard on its own that may affect the fast.
Despite that, only Allah accepts and rejects fast and to him is all good deeds.