Abu Sa'eed Khudari Radiyallahu 'Anhu says:
"When Rasuluilah Sallallahu 'Alayhi Wasallam sat in the rnasjid, he sat in the qarfasaa posture' (JA)
English reference (JA): Book 20, Hadith 122 (JA)
Arabic reference (JA): Book 21, Hadith 129 (JA)