What is the ruling on the prayer of one from whom madhy (prostatic fluid) is discharged during prayer, or immediately after ablution while he is praying, and must he repeat it every time he discovers that?

If the discharge of pre-seminal fluid (madhy) is not continuous, it invalidates wudu' (ablution) and prayer. However, if it is mostly continuous, and it stops for a sufficient time to perform wudu' and prayer, then one must wait for the time it stops. If it does not stop for a sufficient time, then one must perform wudu' for each prayer after its time has begun, along with washing the affected area and binding it with a cloth. What is discharged thereafter does not matter, as Ibn Qudamah said: "A woman with prolonged vaginal bleeding (mustahadah) and a person suffering from urinary incontinence or continuous discharge of pre-seminal fluid... are those whose impurity is continuous, and they cannot maintain their purity. Such a person must perform wudu' for each prayer after washing the affected area, binding it, and taking precautions to prevent the discharge of the impurity as much as possible."