It has been reported from Ummi Salamah Radhiyallahu 'Anha:
"Rasulullah Sallallahu 'Alayhi Wasallam preferred wearing, from among all clothing, the qamis (thowb)" (JA)
English reference (JA): Book 8, Hadith 55 (JA)
Arabic reference (JA): Book 8, Hadith 56 (JA)