'Aayeshah Radiyallahu 'Anha reports:
"Rasulullah Sallallahu 'Alayhi Wasallam did not fast in any month more than in the month of Sha'baan". (JA)
English reference (JA): Book 42, Hadith 290 (JA)
Arabic reference (JA): Book 43, Hadith 307 (JA)