I saw Ibn Abbas sitting on the front of his feet, so I said, "People claim this is rude behavior."He replied, "It is the sunnah of your Prophet ﷺ."
حدثنا يحيى بن إسحاق أخبرنا ابن لهيعة عن أبي الزبير
رأيت ابن عباس يجثو على صدور قدميه فقلت هذا يزعم الناس أنه من الجفاء قال هو سنة نبيك ﷺ
No references are available.
Its isnad is sahih, and it is a repetition of 2855. His saying "he crouches," etc., is the tafsir of iqaa. In ح it appears as "liyajyu," which is a scribal error, corrected from ك.