I said to Abi Ja’far عليه السلام – my clothes come into contact with blood either because of nose-bleeding or some other reason or it comes into contact with some amount of semen … and the time to pray arrives and I forget that my clothes have something (impure in them) – so I pray and then remember after finishing? He said: you repeat the prayer and you wash it off (the impurity) … I said: if I only suspect that it has come into contact with it and am not certain of that, and I try to inspect (to look for it) but find nothing, then I inspect it again after finishing the prayer and find it? he said: you wash it and do not repeat the prayer, I said: how come it is like that (repeat the prayer in the former case and not here)? he said: because you were certain of its purity (when you began praying) and then you doubted later, so it is not appropriate for you to override your certainty because of doubt ever … (Zurara said): what if I see it on my clothes whilst I am praying? He said: you will only break the prayer and repeat it anew if you had doubt about where exactly it was (the location of it – having not found it before) and go on to find it (while praying), but if you had no doubt [of having contracted impurity at all] and then see it (the impurity) – still wet – you cut off your prayer and wash it, then you continue with the same prayer [where you left off], because you just don’t know perhaps it is something that fell on you [while praying], for it is not appropriate for you to override certainty by doubt.