Fathwa, - Performing the ‘Asr Prayer and It Occurs to Him that He Was Performing the Thuhr Prayer

Question
Sometimes when I perform the 'Asr prayer, it occurs to me that I am
performing the Thuhr prayer, if I get distracted or absent minded.
However, I rectify my intention and remind myself that I am performing
the 'Asr prayer. Is my prayer in such a case invalid, given that my
intention has changed ?
Answer
All perfect praise be to Allaah, The Lord of the Worlds. I testify
that there is none worthy of worship except Allaah, and that Muhammad
isHis slave and Messenger.
Being distracted and forgetting one's intention during the prayer does
not invalidate it. What invalidates the prayer is deliberately
changing the intention or intending to change it. It is difficult to
maintain one's intention vivid in the mind throughout the entire
prayer.
Abu Hurayrah reported that the Prophet , said: " When the call for
prayer is pronounced, Satan takes to his heels, passing windwith
noise. When the call is finished, he comes back. When the Iqaamah is
pronounced, he again takes to his heels and, after its completion, he
returns again to interferebetween the (praying) person and his heart,
saying to him: 'Remember this or that thing' (things that the person
could not remember before (the prayer) till he forgets whether he has
offered three or four Rak'ahs. So if one forgets whether hehas prayed
three or four Rak'ahs, he should perform two prostrationsof Sahw (i.e.
forgetfulness). " [Al-Bukhaari and Muslim]
Hence, if the change in the worshipper's intention – the way it was
mentioned by the questioner – was becausehe was distracted or (he
temporarily) forgot his intention, this does not invalidate the
prayer, as stated earlier.
However, if you mean that the worshipper revoked his intention and
intended to perform another prayer, then it surely invalidates the
prayer as in such a case the intention totally changed.
If the questioner means that, during the prayer, he questioned his
intention (and doubted whether he had intendedto perform 'Asr or
Thuhr) and then counted on his doubt (without verifying it), this also
invalidates the prayer as such a prayer lacks the condition of having
an affirmed and assertive intention. However, if he did not act on his
doubt until he realized the truth(about his specific intention), there
is no harm in that.
Allaah Knows best.