Showing off (riya) in worship

Is there any chance of getting blessings from an act ruined by riyaa
if one's intentions change to please Allaah after thethought of riyaa
has already come? For example, I finish recitingQu'raan, and the
thought of riyaa enters my mind. If I immediately fight this thought
with thinking about Allaah, can I still get blessings for my
recitation, or is it completely ruined forever because of riyaa,given
that the act is overand the riyaa thought came after it was already
over?.
Praise be to Allaah.
Shaykh Ibn 'Uthaymeen said:
Showing off may affect worship in three ways:
1 – When the basic motive for worship is to be seen by others, such as
one who stands and prays so that people will see him, and so that
theywill praise him for his prayers. This invalidates the act of
worship.
2 – When it is a factor that develops during theact of worship, i.e.,
if theworshipper is initially sincere in his intention towards Allaah,
then the idea of showing off develops whilst he is doing it. In this
case one of the following two scenarios must apply:
(i) There is no connection between the first part of
his act of worship and the last part, so the first part is valid in
all cases, and thelast part is invalid.
For example: a man has one hundred riyals that he wants to give in
charity, so he gives fifty of them in a sincere act of charity. Then
the idea of showing off develops with regard to the remaining fifty.
So the first was a sound and accepted act of charity, but the last
fifty was an invalid act of charity because the sincerity was mixed
with a desire to show off.
(ii) The first part of the act of worship is connected to
the last part, in which case one of the following two scenarios must
apply:
(a) He wards off the idea of showing off and does not give in to
it, rather he turns away from it and hates it. This does not have any
effect on him, because the Prophet (peace and blessings of Allaah be
upon him) said: "Allaah has forgiven my ummah for what crosses their
minds, so long as they do not act upon it or speak of it."
(b) When he gives in tothis idea of showing off and does not ward
it off.In this case the entire actof worship becomes invalid, because
the first part is connected to the last part. For example, hestarts
the prayer with a sincere intention towards Allaah, then the idea of
showing off develops in the second rak'ah, so the entire prayer
becomes invalid because the first part is connected to the last part.
3 – The idea of showing off develop after the act of worship has
ended. This does not affect it or invalidate it, because it has been
completed soundly, so if showing off occurs after that it does not
affect it.
It is not showing off if a person feels happy that the people come to
know about his worship,because this developed after he has finished
the act of worship.
It is not showing off if a person feels happy because he has done an
act of worship, because that is a sign of his faith. The Prophet
(peace and blessings of Allaah be upon him) said: "Whoever feels happy
because of his good deeds and sad because of his bad deeds, that is
the believer."
The Prophet (peace and blessings of Allaah be upon him) was asked
about that and said: "That is the first glad tidings of the believer."
Majmoo' Fataawa al-Shaykh Ibn 'Uthaymeen, 2/29, 30.