Ibn al-Qayyim, may Allah have mercy on him, writes, “As for knowing the condition of people, this is a tremendous principle required of the scholar and judge. For if he does not have a proper understanding of commanding and forbidding and then he applies one judgment over another, it will cause more harm than benefit. Indeed, if he does not understand the condition of people in the matter, he will make the oppressor appear like the oppressed and vice versa, he will make the truth appear like falsehood and vice versa and he will spread its deceit, treachery, and fraud. He will make heresy appear as righteousness and falsehood appear as truth, and he will dress every lie in a false garment beneath which is sin and wickedness. It is ignorance of the people, their circumstances, their customs, and their traditions for which he cannot distinguish this from that. Rather, the scholar must understand the tendency of people to plot, deceive, and defraud, as well as their customs and traditions. Indeed, the judgment (fatwa) changes with the change of time, place, custom, and circumstance. All of this is from the religion of Allah as has been explained, and success comes from Allah.”

Source: I’lām al-Muwaqqi’īn 4/157

قال ابن القيم رحمه الله وَأَمَّا قَوْلُهُ الْخَامِسَةُ مَعْرِفَةُ النَّاسِ فَهَذَا أَصْلٌ عَظِيمٌ يَحْتَاجُ إلَيْهِ الْمُفْتِي وَالْحَاكِمُ فَإِنْ لَمْ يَكُنْ فَقِيهًا فِيهِ فَقِيهًا فِي الْأَمْرِ وَالنَّهْيِ ثُمَّ يُطَبِّقُ أَحَدَهُمَا عَلَى الْآخَرِ وَإِلَّا كَانَ مَا يَفْسُدُ أَكْثَرَ مِمَّا يَصْلُحُ فَإِنَّهُ إذَا لَمْ يَكُنْ فَقِيهًا فِي الْأَمْرِ لَهُ مَعْرِفَةٌ بِالنَّاسِ تَصَوَّرَ لَهُ الظَّالِمُ بِصُورَةِ الْمَظْلُومِ وَعَكْسُهُ وَالْمُحِقُّ بِصُورَةِ الْمُبْطِلِ وَعَكْسُهُ وَرَاجَ عَلَيْهِ الْمَكْرُ وَالْخِدَاعُ وَالِاحْتِيَالُ وَتَصَوَّرَ لَهُ الزِّنْدِيقُ فِي صُورَةِ الصِّدِّيقِ وَالْكَاذِبُ فِي صُورَةِ الصَّادِقِ وَلَبِسَ كُلُّ مُبْطِلٍ ثَوْبَ زُورٍ تَحْتَهَا الْإِثْمُ وَالْكَذِبُ وَالْفُجُورُ وَهُوَ لِجَهْلِهِ بِالنَّاسِ وَأَحْوَالِهِمْ وَعَوَائِدِهِمْ وَعُرْفِيَّاتِهِمْ لَا يُمَيِّزُ هَذَا مِنْ هَذَا بَلْ يَنْبَغِي لَهُ أَنْ يَكُونَ فَقِيهًا فِي مَعْرِفَةِ مَكْرِ النَّاسِ وَخِدَاعِهِمْ وَاحْتِيَالِهِمْ وَعَوَائِدِهِمْ وَعُرْفِيَّاتِهِمْ فَإِنَّ الْفَتْوَى تَتَغَيَّرُ بِتَغَيُّرِ الزَّمَانِ وَالْمَكَانِ وَالْعَوَائِدِ وَالْأَحْوَالِ وَذَلِكَ كُلُّهُ مِنْ دِينِ اللَّهِ كَمَا تَقَدَّمَ بَيَانُهُ وَبِاَللَّهِ التَّوْفِيقُ

4/157 إعلام الموقعين عن رب العالمين تغيير الفتوى واختلافها