Sahih al-Bukhari 827
صحيح البخاري#827SahihNarrated `Abdullah bin `Abdullah:I saw `Abdullah bin `Umar crossing his legs while sitting in the prayer and I, a mere youngster in those days, did the same. Ibn `Umar forbade me to do so, and said, "The proper way is to keep the right foot propped up and bend the left in the prayer." I said questioningly, "But you are doing so (crossing the legs)." He said, "My feet cannot bear my weight
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 10:221