كتاب البيوع
Read the English translation first, with the original Arabic directly underneath.
Narrated An-Nu`man bin Bashir:
The Prophet (ﷺ) said "Both legal and illegal things are obvious, and in between them are (suspicious) doubtful matters. So whoever forsakes those doubtful things lest he may commit a sin, will definitely avoid what is clearly illegal; and whoever indulges in these (suspicious) doubtful things bravely, is likely to commit what is clearly illegal. Sins are Allah's Hima (i.e. private pasture) and whoever pastures (his sheep) near it, is likely to get in it at any moment."
الْحَلاَلُ بَيِّنٌ، وَالْحَرَامُ بَيِّنٌ وَبَيْنَهُمَا أُمُورٌ مُشْتَبِهَةٌ، فَمَنْ تَرَكَ مَا شُبِّهَ عَلَيْهِ مِنَ الإِثْمِ كَانَ لِمَا اسْتَبَانَ أَتْرَكَ، وَمَنِ اجْتَرَأَ عَلَى مَا يَشُكُّ فِيهِ مِنَ الإِثْمِ أَوْشَكَ أَنْ يُوَاقِعَ مَا اسْتَبَانَ، وَالْمَعَاصِي حِمَى اللَّهِ، مَنْ يَرْتَعْ حَوْلَ الْحِمَى يُوشِكْ أَنْ يُوَاقِعَهُ