How much food should be given when atoning for what one swore about?

Sunan Ibn Majah · Book 11 · Hadith 2112

حَدَّثَنَا الْعَبَّاسُ بْنُ يَزِيدَ، حَدَّثَنَا زِيَادُ بْنُ عَبْدِ اللَّهِ الْبَكَّائِيُّ، حَدَّثَنَا عُمَرُ بْنُ عَبْدِ اللَّهِ بْنِ يَعْلَى الثَّقَفِيُّ، عَنِ الْمِنْهَالِ بْنِ عَمْرٍو، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ كَفَّرَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ بِصَاعٍ مِنْ تَمْرٍ وَأَمَرَ النَّاسَ بِذَلِكَ فَمَنْ لَمْ يَجِدْ فَن…

It was narrated that Ibn Abbas said: "The Messenger of Allah (ﷺ) offered expiation of a Sa' of dates, and he enjoined the people to do likewise. Whoever does not have that (must give) half a Sa' of wheat."