Abdullah bin Abbas reported,

Ibn Abbas said, "If it pleases you to know the ignorance of the Arabs, then read what comes after verse one hundred and thirty in Surah al-Anam, 'Lost indeed are those who have killed their children foolishly, without knowledge' up to His saying 'they have certainly gone astray and were not rightly guided'" [Anam 6:140].

Azami 12318

Sahih

عن ابن عباس قال

إذا سرك أن تعلم جهل العرب، فاقرأ ما فوق الثلاثين ومئة في سورة الأنعام {قد خسر الذين قتلوا اولادهم سفها بغير علم} إلى قوله {قد ضلوا وما كانوا مهتدين}.

الأعظمي 12318صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Tafsir of the great Quran
Chapter
Virtues of Surah Baqarah
Section
His saying, "Those will have lost who killed their children in foolishness without knowledge and prohibited what Allah had provided for them, inventing falsehood about Allah. They have gone astray and were not guided"
Numbering
Jami al-Kamil 12318 (2nd edition)
Azami 12318