(So he (the disbeliever) neither believed nor prayed! But on the contrary, he belied and turned away!)(75:31-32),
وَأَعْطَى قَلِيلاً وَأَكْدَى
(And gave a little, then stopped) Ibn `Abbas said, "Gave a little, then stopped giving." Similar was said by Mujahid, Sa`id bin Jubayr, `Ikrimah, Qatadah and several others. `Ikrimah and Sa`id said: "Like the case of a people who dig a well, during the course of which they find a rock preventing them from completing their work. So they say, `We are finished' and they abandon the work." Allah's statement,
وَأَنَّ سَعْيَهُ سَوْفَ يُرَىٰ (and that his effort will soon be seen...53:40) In other words, outer actions of a person are not sufficient. Allah will take into account the real, inner motive and driving force behind them whether they were performed with the sincerity of purpose, or they were done with some ulterior motive. The Holy Prophet t is reported to have said:
اِنَّمَا الاَعمَال بِالنِّیَّاتِ
"Actions shall be judged only by the intentions."
That is, the outer aspect of actions is not sufficient. The inner aspect is also necessary. Actions must be performed purely for the good pleasure of Allah and in compliance with His command.
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 35–41
There are many who become inclined towards the Truth, but only to a certain extent. Then the compulsions of their interests become too strong for them and they revert to their original position. In order to justify and explain their wrong behaviour, such people devise different types of engaging ‘beliefs’. But this only increases their guilt because this amounts to adding insult to injury.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.