[On Belief]
وَالإيمَانُ فِي الشَّرْعِ: هُوَ التَّصْدِيقُ بِمَا جَاءَ النَّبِيُّ عَلَيْهِ الصلاةُ والسَّلاَمُ بِهِ مِنْ عِنْدِ اللَّهِ تَعَالَى، وَالإقْرَارُ بِهِ، وَأَمَّا الأَعْمَالُ فَهِيَ تَتَزَايَدُ فِي نَفْسِهَا، وَالإِيمَانُ لاَ يَزِيدُ وَلاَ يَنْقُصُ. وَالإِيمَانُ وَالإِسْلاَمُ وَاحِدٌ. فَإِذَا وُجِدَ مِنَ الْعَبْدِ التَّصْدِيقُ والإقْرَارُ صَحَّ لَهُ أَنْ يَقُولَ: أَنَا مُؤْمِنٌ حَقّاً، وَلاَ يَنْبَغِي أَنْ يَقُولَ: أَنَا مُؤْمِنٌ إِنْ شَاءَ اللَّهُ.
028- Belief (īmān) is assent (taṣdīq) to that which he brought from God, the exalted, and confession (iqrār) of it. As for works, they increase in and of themselves, but belief (īmān) neither increases nor decreases. And belief (īmān) and islam are one. And whenever assent and confession are found in a creature, it is right for him to say, “I am a believer, (mūʾmin) if God, the exalted, wills.”