Abdullah bin Maqil reported,

I sat with Kaab bin Ujra رضي الله عنه and asked him about the expiation. He said, "It was revealed concerning me specifically, but it applies to all of you generally. I was brought to the Messenger of Allah ﷺ with lice falling onto my face."The Prophet ﷺ said, "I did not realize the suffering had reached such a point with you," or he said, "I did not realize the hardship had reached such a point with you. Can you find a sheep?"I replied, "No."He said, "Then fast three days, or feed six poor people, giving each one half a saa."

Bukhari 1816

Sahih

حدثنا أبو الوليد حدثنا شعبة عن عبد الرحمن بن الأصبهاني

عن عبد الله بن معقل قال

جلست إلى كعب بن عجرة رضي الله عنه فسألته عن الفدية فقال نزلت في خاصة وهي لكم عامة حملت إلى رسول الله ﷺ والقمل يتناثر على وجهي فقال ما كنت أرى الوجع بلغ بك ما أرى أو ما كنت أرى الجهد بلغ بك ما أرى تجد شاة فقلت لا فقال فصم ثلاثة أيام أو أطعم ستة مساكين لكل مسكين نصف صاع

البخاري 1816صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Bukhari
Book
Confined person
Chapter
Feeding for fidya is half a saa
Numbering
Darussalam 1816
Bukhari 1816