Conditions for the validity of Salaah

Salaah with mazi on ones clothing

Q: Yesterday, when I went to toilet, I found stains of pre-cum (mazi) [I have this problem that often it comes out unintentionally). The stain was very small, probably smaller than a drop of water. Nevertheless, as I was in a hurry to join the Asr Salah in jamah, I forgot to change my underwear and even forgot to wash the stain. In this condition I prayer the Asr, Mugrib, Esha and todays Fajr Salah before recalling the incident. Now my question is should I repeat the four Salah prayed in the above mentioned condition or was my Salah valid. Can you also advise me on what to do for the problem of the mazi coming out.

Combining Salaahs

Q: You have mentioned that "One wudhu will suffice for both the namaazes if they are read in the time of Esha" but my question is that what if the the both salaah Maghrib & Esha are combined and prayed in Maghrib time, will the wudhu of Maghrib suffice for Esha salaah? 

Last time of Maghrib Salaah

Q: If one is for example about to pray Maghrib after the time of those who calculate end of maghrib time with 12 degree or 15 degree, but one is still before the time of 18 degree, should one make the intention for the adh'aa of that days Maghrib or for the qadh'aa of that days Maghrib ? For example Maghrib time is at 20:00 according to 12 degree Maghrib ends 21:15, according to 15 degree, it ends 21:40 and according to 18 degree it ends at 22:00. Now how must I make the intention if I would start praying Maghrib at 21:25 or at 21:45? Because when I am in such situation because of the waswas of what to do, I pray one time as adh'aa and after it repeat one time as qadh'aa. Should I make intention to pray the current day Maghrib, or the currents day qadh'aa of Maghrib in such a case? Or can I make intention like ''I want to pray the Fard of Maghrib of this day, which I have not prayed yet'' does such intention then count for both i.e. if it was a adh'aa it will count for adh'aa, and if it was a qadh'aa it will count for a qadh'aa? Does such an intention count according to Abu Hanifa, Imaam Muhammad, Abu Yusuf? Should I avoid that during my salaah in the above case of Maghrib that the specific time of 12 and 15 degrees falls in the middle of my salaah, since according to Abu Hanifa entering a new time during salaah would make the prayer faasid?