Sahih al-Bukhari 3524
Narrated Ibn `Abbas:
If you wish to know about the ignorance of the Arabs, refer to Surat-al-Anam after Verse No. 130:-- 
Indeed lost are those who have killed their children From folly without knowledge and have forbidden 
that which Allah has provided for them, inventing a lie against Allah. They have indeed gone astray 
and were not guided.' (6.14)
حَدَّثَنَا أَبُو النُّعْمَانِ، حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ أَبِي بِشْرٍ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ إِذَا سَرَّكَ أَنْ تَعْلَمَ جَهْلَ الْعَرَبِ فَاقْرَأْ مَا فَوْقَ الثَّلاَثِينَ وَمِائَةٍ فِي سُورَةِ الأَنْعَامِ ‏{‏قَدْ خَسِرَ الَّذِينَ قَتَلُوا أَوْلاَدَهُمْ سَفَهًا بِغَيْرِ عِلْمٍ‏}‏ إِلَى قَوْلِهِ ‏{‏قَدْ ضَلُّوا وَمَا كَانُوا مُهْتَدِينَ‏}‏‏.‏