It wasnarrated from Abu Hurairah that the Messenger of Allah (ﷺ)said:
"If a person prays in public and does it well, and he prays insecret and does it well, then Allah says: 'This man is truly Myslave.'" (JA)
English reference (JA): Vol. 5, Book 37, Hadith 4200 (JA)
Arabic reference (JA): Book 37, Hadith 4340 (JA)