Prohibition of eating the core until its sides are eaten.

Saʿīd b. ʿĀmir > Shuʿbah > ʿAṭāʾ b. al-Sāʾib > Saʿīd b. Jubayr > Ibn ʿAbbās

"The Messenger of Allah ﷺ was presented with a handful or a piece of bread, and he said, 'Eat from its edges or sides and do not eat from its center, for blessings descend in its center.'" – Sound Chain

أَخْبَرَنَا سَعِيدُ بْنُ عَامِرٍ عَنْ شُعْبَةَ عَنْ عَطَاءِ بْنِ السَّائِبِ عَنْ سَعِيدِ بْنِ جُبَيْرٍ عَنْ ابْنِ عَبَّاسٍ

أَنَّ رَسُولَ اللَّهِ ﷺ أُتِيَ بِجَفْنَةٍ أَوْ قَالَ قَصْعَةٍ مِنْ ثَرِيدٍ فَقَالَ كُلُوا مِنْ حَافَاتِهَا أَوْ قَالَ جَوَانِبِهَا وَلَا تَأْكُلُوا مِنْ وَسَطِهَا فَإِنَّ الْبَرَكَةَ تَنْزِلُ فِي وَسَطِهَا – إسناده صحيح