Musannaf Ibn Abi Shayba 33:1324

Abu al-Ahwas narrated to us, from Mansur, from Hilal ibn Yasaf, who said: It was narrated to me that ‘Isa ibn Maryam used to say: "When one of you gives charity, let him give with his right hand and conceal it from his left. And when it is a day of fasting for one of you, let him apply oil and wipe his lips with the oil, so that when the onlooker looks at him, he does not see that he is fasting. And when he prays in his house, let him draw his curtain over himself, for indeed, praise is apportioned just as provision is apportioned."