Bara bin Azib reported,

In those days, when a man fasted and then fell asleep, he would not eat again until the same hour the following day. Now Sirmah bin Qays Ansari came to his wife while he was fasting and asked her, "Do you have anything to eat?"She said, "No, but perhaps I can go and find something for you."So she went out, and sleep overcame him. When she returned she said, "What a shame for you!"By midday he had fainted, for he used to spend his day working on his land. This was mentioned to the Prophet ﷺ, and then came the revelation, "It has been made lawful for you on the night of the fast to approach your wives" [Baqarah 2:187], and he recited on to the words, "from the Fajr" [Baqarah 2:187].

حدثنا نصر بن علي بن نصر الجهضمي أخبرنا أبو أحمد أخبرنا إسرائيل عن أبي إسحق

عن البراء قال

كان الرجل إذا صام فنام لم يأكل إلى مثلها وإن صرمة بن قيس الأنصاري أتى امرأته وكان صائما فقال عندك شيء قالت لا لعلي أذهب فأطلب لك شيئا فذهبت وغلبته عينه فجاءت فقالت خيبة لك فلم ينتصف النهار حتى غشي عليه وكان يعمل يومه في أرضه فذكر ذلك للنبي ﷺ فنزلت {أحل لكم ليلة الصيام الرفث إلى نسائكم} قرأ إلى قوله {من الفجر}