They apply their minds to deceiving Allah, AL-'Alim (the Omniscient), Who knows - Surah Al-Baqarah ayat 9 in Tafsir

﴿يُخَٰدِعُونَ ٱللَّهَ وَٱلَّذِينَ ءَامَنُواْ وَمَا يَخۡدَعُونَ إِلَّآ أَنفُسَهُمۡ وَمَا يَشۡعُرُونَ ﴾
[البَقَرَة: 9]

They apply their minds to deceiving Allah, AL-'Alim (the Omniscient), Who knows what is secretly suggested to the mind, and to deceive those whose hearts have been impressed with the image of religious and spiritual virtues, when in fact, they only deceive themselves, failing to perceive

﴿يخادعون الله والذين آمنوا وما يخدعون إلا أنفسهم وما يشعرون﴾ [البَقَرَة: 9]

Dr Kamal Omar
They deceive Allah and those who have Believed, in reality they deceive not but their ownselves and they realise not

Dr Laleh Bakhtiar
They seek to trick God and those who believed while they deceive none but themselves, but they are not aware

Dr Munir Munshey
They (attempt to) deceive Allah and the believers; in reality, they deceive no one but themselves. They just do not realize

Edward Henry Palmer
They would deceive God and those who do believe; but they deceive only themselves and they do not perceive

Farook Malik
They try to deceive Allah and the believers. However, they deceive none except themselves yet they do not realize it

George Sale
they seek to deceive God, and those who do believe, but they deceive themselves only, and are not sensible thereof

Maududi
They thus try to deceive Allah and the Believers, but they succeed in deceiving none except themselves and they realize it not