(145) باب سُنَّةِ الْجُلُوسِ فِي التَّشَهُّدِ
Narrated `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."
Reference: Sahih al-Bukhari 827
In-book reference: Book 10, Hadith 221
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 12, Hadith 790