It wasnarrated from Abu Sa'ib that he heard Abu Hurairah say:
"TheMessenger of Allah (ﷺ) said: 'Whoever performs a prayer in whichhedoes not recite Ummul Qur'an (the Mother of the Qur'an, i.e.,Al-Fatihah), it is deficient; not complete.'" I said: 'O AbuHurairah,sometimes I am behind the Imam. He pressed my forearm andsaid: 'OPersian! Recite it to yourself.'" (JA)
English reference (JA): Vol. 1, Book 5, Hadith 838 (JA)
Arabic reference (JA): Book 5, Hadith 887 (JA)