Ibn Zubair used to provide us with dates during the time that the people were hard pressed because of famine (Once) as we were busy in eating there happened to appear before us Ibn 'Umar. He said: Don't eat two dates together, for Messenger of Allah ﷺ forbade eating them together but only after seeking permission from his brother (partner). Shu'ba said: I do not think these words pertaining to seeking permission but from the words of Ibn 'Umar.
وَقَدْ كَانَ أَصَابَ النَّاسَ يَوْمَئِذٍ جُهْدٌ وَكُنَّا نَأْكُلُ فَيَمُرُّ عَلَيْنَا ابْنُ عُمَرَ وَنَحْنُ نَأْكُلُ فَيَقُولُ لاَ تُقَارِنُوا فَإِنَّ رَسُولَ اللَّهِ ﷺ نَهَى عَنِ الإِقْرَانِ إِلاَّ أَنْ يَسْتَأْذِنَ الرَّجُلُ أَخَاهُ قَالَ شُعْبَةُ لاَ أُرَى هَذِهِ الْكَلِمَةَ إِلاَّ مِنْ كَلِمَةِ ابْنِ عُمَرَ يَعْنِي الاِسْتِئْذَانَ