صحيح البخاري
Sahih Bukhari
كتاب تقصير الصلاة
The Book of Abridged Or Shortened Prayers (At-Taqsir)
باب إذا صلى قاعدا ثم صح أو وجد خفة تمم ما بقي:
Chapter. Whoever starts his Salat (prayer) sitting (because of ailment) and then during the Salat (prayer) feels better, can finish the rest while standing. 138
