Al-Jawāb as-Sahīh li-man baddala dīn al-Masīh - Ibn Taimiya - (1/128)

He, Exalted is He, also says:

“Who could be more unjust than one who invents a lie about Allah and rejects the truth when it comes to him? Is not Hell an abode for the disbelievers? Whereas the one who brought the truth and those who affirmed it—such people are the truly God-fearing. For them is whatever they desire with their Lord; that is the reward of those who do good.” (39:32-34)

And He, the Exalted, says:

“On the Day of Resurrection you will see those who lied against Allah: their faces will be blackened. Is not Hell an abode for the arrogant?” (39:60)

Lying is the root of all evil, and the gravest lie is to fabricate against Allah, Mighty and Majestic. Truthfulness is the root of all good, and the highest form of truthfulness is to speak truthfully about Allah, Blessed and Exalted.

In the two Ṣaḥīḥ collections it is related from ʿAbdullāh ibn Masʿūd (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said:

“Hold fast to truthfulness, for truthfulness leads to righteousness, and righteousness leads to Paradise. A man continues to speak the truth and to pursue truthfulness until he is recorded with Allah as a speaker of unalloyed truth. And beware of lying, for lying leads to wickedness, and wickedness leads to the Fire. A man persists in lying and in the pursuit of falsehood until he is recorded with Allah as an inveterate liar.”

وَقَالَ تَعَالَى: {فَمَنْ أَظْلَمُ مِمَّنْ كَذَبَ عَلَى اللَّهِ وَكَذَّبَ بِالصِّدْقِ إِذْ جَاءَهُ أَلَيْسَ فِي جَهَنَّمَ مَثْوًى لِلْكَافِرِينَ - وَالَّذِي جَاءَ بِالصِّدْقِ وَصَدَّقَ بِهِ أُولَئِكَ هُمُ الْمُتَّقُونَ - لَهُمْ مَا يَشَاءُونَ عِنْدَ رَبِّهِمْ ذَلِكَ جَزَاءُ الْمُحْسِنِينَ} [الزمر: ٣٢ - ٣٤] . وَقَالَ تَعَالَى: {وَيَوْمَ الْقِيَامَةِ تَرَى الَّذِينَ كَذَبُوا عَلَى اللَّهِ وُجُوهُهُمْ مُسْوَدَّةٌ أَلَيْسَ فِي جَهَنَّمَ مَثْوًى لِلْمُتَكَبِّرِينَ} [الزمر: ٦٠] . فَالْكَذِبُ أَصْلٌ لِلشَّرِّ، وَأَعْظَمُهُ الْكَذِبُ عَلَى اللَّهِ عَزَّ وَجَلَّ، وَالصِّدْقُ أَصْلٌ لِلْخَيْرِ، وَأَعْظَمُهُ الصِّدْقُ عَلَى اللَّهِ تَبَارَكَ وَتَعَالَى. وَفِي الصَّحِيحَيْنِ: عَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ، رَضِيَ اللَّهُ عَنْهُ، عَنِ النَّبِيِّ، صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ، أَنَّهُ قَالَ: «عَلَيْكُمْ بِالصِّدْقِ ; فَإِنَّ الصِّدْقَ يَهْدِي إِلَى الْبِرِّ، وَإِنَّ الْبِرَّ يَهْدِي إِلَى الْجَنَّةِ، وَلَا يَزَالُ الرَّجُلُ يَصْدُقُ وَيَتَحَرَّى الصِّدْقَ، حَتَّى يُكْتَبَ عِنْدَ اللَّهِ صَدِّيقًا، وَإِيَّاكُمْ وَالْكَذِبَ ; فَإِنَّ الْكَذِبَ يَهْدِي إِلَى الْفُجُورِ، وَإِنَّ الْفُجُورَ يَهْدِي إِلَى النَّارِ، وَلَا يَزَالُ الرَّجُلُ يَكْذِبُ وَيَتَحَرَّى الْكَذِبَ حَتَّى يُكْتَبَ عِنْدَ اللَّهِ كَذَّابًا» .